Across:
1 Going on the beer (DRINKING) for liquid refreshment (WATER)? (DRINKING WATER) Go to The Tap for that! (DRINKING WATER),
10 It’s not natural, in a mechanical way (ROBOTIC), to turn away from contributor (‘turn’ away from ‘contributor’ = coribto = ROBOTIC),
11 Less mature (YOUNGER) guy, one (guy one) mixing up (= anagram indicator) (guy one = YOUNGE-) arithmetic (from the 3Rs = -R) (YOUNGER),
12 Some undermine a technology (some ‘undermiNE A Technology’ = NEAT) in Trim (NEAT),
13 You’ll need this to start on all sides today (DRINK on all sides of today’s grid)? Spirit! (DRINK),
15 Pianist is out of inspiration (‘pianist’ is out of ‘inspiration’ = rion = IRON) producing heavy metal (IRON),
17 As well as (and) digging up (= reverse indicator) (and = DNA) evidence the police could use in an investigation (DNA),
19 Spain and Portugal (IBERIA) and more than half of Russia (Siberia) is leaderless (s) (‘Siberia’ without ‘s’ = IBERIA),
21 Relative (papa) is not finished (a) (‘papa’ without ‘a’ = PAP-) with biography, the last (‘biographY’ the last = -Y-) on Irish King (Irish ‘King = ‘Rí’ = -RI) (PAPYRI) – what the old Egyptian writers wrote on (PAPYRI),
22 A couple of purchases (buy + buy) reported (= homophone indicator) (“buy buy” = “bye bye” = BYE-BYE-) at the opening of sale (the opening of ‘Sale’ = -S) (BYE-BYES) in the nursery – one might say on the way out? (in children’s nursery one might say = BYE-BYES on the way out),
23 Wash your mouth out (GARGLE) with local drink (local ‘drink’ = GARGLE),
25 Turns up (= reversal indicator), the man upstairs (God = DOG) took drugs (pot = TOP) (TOP DOG) with the champion boxer perhaps (TOP DOG),
27 Urgent call (SOS) from inside espresso shop (from inside ‘espresSO Shop’ = SOS),
29 Old (O-) writer (-PEN) (OPEN) not afraid to call a spade a spade (OPEN),
30 What you might find in spring (WATER) or at the end of 1 across (end of ‘drinking water’ = WATER),
31 Milky-white stone (OPAL) part of sago palms (found in ‘sagO PALms’ = OPAL),
34 A danger (a danger) touring (= anagram indicator) (a danger = GRENADA) in the Caribbean (GRENADA),
35 Germs removed from dressing room (‘germs’ removed from ‘dressing room’ = dsinroo = INDOORS) within a building (INDOORS),
36 Vermouth (DRINK-) and gin (gin = -ING) cocktail (= anagram indicator) on the house at The Thatch (STRAW is part of a thatched roof) (DRINKING STRAW) produced by an environmentally suspect sucker perhaps (DRINKING STRAW).
Down:
2 Presumably, this was opened to get the First Lady out to start a new life (Adam/Eve ... RIB CAGE) with kid (kid/joke = RIB) from lock-up (CAGE) (RIB CAGE),
3 Catches (NETS) reviews (= reversal indicator) of characters in The West End (in ‘the weST ENd’ = sten = NETS),
4 Bouncers might request this if you’re going to music halls perhaps to see bands (ID CARDS) at The Centre from Dido (the centre from ‘dIDo’ = ID) to Queen (playing CARD) (ID CARD),
5 Boatman leaves Guantanamo Bay (‘boatman’ leaves ‘Guantanamo Bay’ = guanay = GUYANA) for country in South America (GUYANA),
6 Like something in 13 across (a rum ‘drink’ = ‘a rum’ = ARUM) produced by one from Lily’s family (ARUM),
7 Gary Lee (Gary Lee) is travelling (= anagram indicator) (Gary Lee = EAGERLY) with anticipation (EAGERLY),
8 Enjoying a happy hour (DRINKING) with relatives (sons = SON-S) outside front garden (front/first letter of ‘Garden’ = -G-) (DRINKING SONGS) to the sounds of Whiskey in the Jar and Red, Red Wine (DRINKING SONGS),
9 Where you’d expect to find a port (DRINKING GLASS) for a schooner (DRINKING GLASS),
14 Press coverage (INK-) on lawyer (Barrister-at-Law = -BL-) with what’s Biblical? (Old Testament = -OT) (INKBLOT) That’s a test of the psychologists! (INKBLOT),
16 Turns up (= reverse indicator), the foreign (‘the’ Spanish = el = -LE) B&B (B&B = B-B-) welcomes initial inclusion (initial ‘Inclusion’ = -I-) (BIBLE) in good books (good books = BIBLE),
18 A jar (MASON jar) with two close relatives? (ma + son = MASON),
20 Squid coming off quayside (‘squid’ coming off ‘quayside’ = aye = AYE)? Yes, in a boat! (AYE),
21 Animal kept for companionship (PET) up (= reverse indicator) in Mount Ephraim (up in ‘mounT EPhraim’ = tep = PET),
24 Does mate (doe’s mate = ROE DEER) get lobster, eggs (lobster eggs = ROE) from venison producer? (DEER) (ROE DEER),
26 Academic paper (DIPLOMA) produced by nerds from Promised Land? (‘nerds’ from ‘Promised Land’ = pomidla = DIPLOMA),
27 Presumably, has been cured (SALAMI) by doctors closing (‘doctorS’ closing = S-) Academy (-A-), Islamic Centre (‘isLAMic’ centre = -LAM-) and Institute (-I) (SALAMI),
28 Using needle (SEWING) in final games (final ‘gameS’ = S-), for example (e.g. = E-G), protecting game, set and match (game, set and match = -WIN-) (SEWING),
32 Country dance partner (BARN dance) produced a cover of The Animals (BARN),
33 Change one’s story (EDIT) covered in cancelled itinerary (part in ‘cancellED ITinerary’ = EDIT).