Across:
1 Retweet (R-T) about type of wine (rosé) served up (= reversal indicator) (rosé = -ESOR-) (RESORT) for the tourists to enjoy (RESORT),
4 Hurry up (STEP ON IT) and put your foot down (STEP ON IT),
9 Assumes an upright position (STANDS) getting par coming out of sand traps (‘par’ coming out of ‘sand traps’ = sndtas = STANDS).
10 Works on firing kit (works on firing kit/armour = ARMOURER) manager of Arsenal? (ARMOURER),
12 Given the job (APPOINTEE) and its pressure (-P-) – what’s the objective (-POINT-) taking ecstasy (-E-) in A&E? (A-E) (APPOINTEE),
13 Order (O-) from judge (-RATE) (ORATE) to speak up (ORATE),
14 National anthem (COUNTRY MUSIC) of Liechtenstein, for instance (COUNTRY), and 21 across? (MUSIC) (COUNTRY MUSIC),
18 They have the final say (CASTING VOTES) of who’s going to be in the picture? (they have the CASTING VOTES),
21 What to make with The Bell (MUSIC) – it’s horrid from Iris Murdoch? (it’s ‘horrid’ from ‘Iris Murdoch’ = ismuc = MUSIC),
22 Heard (= homophone indicator) eau de cologne (‘scent’ = ‘sent’ = -SENT-) found in another (= anagram indicator) aisle (aisle = ES-IAL) (ESSENTIAL) is a must-have (ESSENTIAL),
24 It means getting through (SURVIVAL) to head of state (head of ‘State’ = S-) from old city (-UR-) opposed (against/versus = -V-) to challenger (rival) losing the head (r) (‘rival’ without ‘r’ = -IVAL) (SURVIVAL),
25 Therapist takes off hat (‘therapist’ takes off ‘hat’ = erpist = PRIEST) to minister (PRIEST),
26 Omen (-SIGN-) in knocked back (= reverse indicator) grass (reed = DE-ER) (DESIGNER) alludes to The Creator (DESIGNER),
27 Hired (RENTED) bar from bartender (‘bar’ from ‘bartender’ = tender = RENTED)
Down:
1 Go through the books (RESEARCH) for damaged (= anagram indicator) cars here (cars here = RESEARCH),
2 A (-A-) foreign politician (-MP) consumed by beer (stout = ST- OUT) (STAMP OUT) and scotch (scotch/put an end to = STAMP OUT),
3 The bones (RADII) of broadcasting unit (radio) briefly (o) (‘radio’ without ‘o’ = RADI-) close to his heart (‘hIs’ heart = -I) (RADII),
5 Most (d) of 8 down (turned) (‘turned’ without ‘d’ = TURNE-) having party (Democratic Unionist Party = DUP = -D UP) at the front of the plane (NOSE) (TURNED-UP NOSE) showed contempt (TURNED-UP NOSE),
6 Evidence (proof = PRO-OF-) about 1,000 (1,000 = -K-) from Ireland (Ireland domain = i.e.= -IE-) and five (-V) (PROKOFIEV) born in Ukraine, who composed music? (PROKOFIEV),
TO CHANGE ABOVE
7 Roman (roman) order (= anagram indicator) (roman = NORMA-) left (-L) (NORMAL) as usual (NORMAL),
8 Study (den = -NED) Russia (RU = -UR-) and Turkey primarily (‘Turkey’ primarily = T-) raising all (= reverse all indicator) (TURNED) that went sour (TURNED),
11 Wander off (stray) ignoring reading (r) (‘stray’ without ‘r’ = STAY-) at school (-S) – oddly (= anagram indicator), each pet (each pet = THE PACE) keeps up (STAYS THE PACE),
15 Strange (= anagram indicator) night chat (night chat = THATCHING) is keeping a roof over one’s head (THATCHING),
16 Emailed (S-ENT) over tax (DIRT tax) return = (reverse indicator) (DIRT = -TRID-) (STRIDENT) – it sounds really harsh! (STRIDENT),
17 Lose it (lose it) badly (= anagram indicator) (lose it = ISOL-TE-) over a (-A-) final demand (final ‘demanD’ = -D) (ISOLATED) or be cut off (ISOLATED),
19 Occupied (AMUSED) by a (A-) thought (-MUSED) (AMUSED),
20 Teacher (-SIR-) is one (-I-) taken in by sailor (Ordinary Seaman = OS = O-S) (OSIRIS) – someone worshiped in the underworld (OSIRIS),
23 Bottle (NERVE) of the gas taken from The Avengers? (‘the gas’ taken from ‘The Avengers’ = vener = NERVE).