Across:
1 Stage-managed without means – a (‘stage-managed’ without ‘means a’ = tgaged = GADGET) labour-saving innovative device (GADGET),
4 Takes out (OFFLOADS) to party (Fianna Fáil = -FF-) after (= position indicator) opening outlet (opening ‘Outlet’ = O-) and taking on a lot (a lot = -LOADS) (OFFLOADS),
9 Danish (Danish PASTRY) model (= anagram indicator) parts (parts = PASTR-) with Yankee (-Y) (PASTRY),
10 Two different holidays (leave + out = LEAVE OUT) to forget (LEAVE OUT),
12 Completely reserved (BOOKED OUT) Dubliners, for example (James Joyce’s Dubliners = BOOK-), employed by the paper (-ED) at the end of 10 across (end of ‘leave out’ = OUT) (BOOKED OUT),
13 A sad feeling (downer) coming off the summit (d) (‘downer’ without ‘d’ = OWNER) with title-holder (OWNER),
14 A chap that’s never in the public eye (INVISIBLE MAN) won’t leave a trace of his movements (INVISIBLE MAN),
18 Sounds like (= homophone indicator) principal (‘principal’ = ‘principle’) favouring those with brawn (MIGHT IS RIGHT) in theory? It lets those holding the birch to go unchallenged! (MIGHT IS RIGHT),
21 Most coming from megastore (‘most’ coming from ‘megastore’ = egare = AGREE) of the same opinion (AGREE),
22 Working in the catering college presumably (LECTURING) with the French (‘the’ French = LE-) saving the bacon (curing = -C-URING) around bone (T bone = -T-) (LECTURING),
24 Regular publications (WEEKLIES) producing unconvincing (weak) reports (= homophone indicator) (‘weak’ = ‘week’ = WEEK-) on fiction (-LIES) (WEEKLIES),
25 No art in satirical (no ‘art’ in ‘satirical’ = siical = SILICA) piece coming from The Stones perhaps (SILICA),
26 Precious stuff (GOLD) produced by chippy (DUST) (GOLD DUST) like hen’s teeth (like hen’s teeth / GOLD DUST),
27 Turns up, the (the) heartless (h) (‘the’ without ‘h’ = te = -ET) legend (‘leG’ end = -G-) found in American city (NYC = CY-N-) (CYGNET) produced a flighty youngster who enjoys swimming (CYGNET).
Down:
1 Strange (= anagram indicator) logic (logic = GO -LIC) going over heads of people upholding balance (heads of ‘People Upholding Balance’ = PUB-) (GO PUBLIC) to issue a statement (GO PUBLIC),
2 Detectives (DIs = DIS-) work out (-SOLVE) (DISSOLVE) break-up? (DISSOLVE),
3 Hair-raising (EERIE) caps removed from earpieces? (‘caps’ removed from ‘earpieces’ = eriee = EERIE),
5 What you might experience with those tight Brogans? (FEEL THE PINCH with those tight brogan shoes) Perceive knowledge gained over time of financial hardship! (FEEL THE PINCH),
6 Exist without anything else other than Nitrogen, Oxygen, Carbon Dioxide and Argon mostly? (Live on the constituents of ‘air’/ Nitrogen, Oxygen, Carbon Dioxide and Argon mostly = LIVE ON AIR) It’s not recorded! (LIVE ON AIR),
7 Nuts (ACORNS) for the origins of The Oaks (ACORNS),
8 Tries a (tries a) soup (= anagram indicator) (tries a = SATIRE) produced by Swift, for one (produced by Jonathan Swift, for one SATIRE),
11 Doctor (-MB), is that woman (SHE-) going with lieutenant (-LT-) occupying South Africans (Boers = BO- -ERS) (BOMB SHELTERS) in secure locations during a raid? (BOMB SHELTERS),
15 Endless (end ‘lesS’ = S-) Trim (s) spouses (wives) (‘wives’ without ‘s’ = -WIVE-) from backward (= reverse indicator) secluded valley (dell = -LLED) (SWIVELLED) did an about turn (SWIVELLED),
16 One getting fired (IGNITION) for scrubbing Alps from oil paintings (scrubbing ‘Alps’ from ‘oil paintings’ = oiinting = IGNITION),
17 Still (STAGNANT), it’s a party (STAG- party) for mum’s mum (-NAN-) at the Central Hotel (central ‘hoTel’ = -T) (STAGNANT),
19 Skint from water-skiing (‘skint’ from ‘water-skiing’ = waerig = EARWIG) – that’s a bug (EARWIG),
20 Adore (adore) novel (= anagram indicator) (adore = ORDEA-) following K (-L is following ‘k’) (ORDEAL) in The Trial (ORDEAL),
23 Scotland is not part of dysfunctional (‘Scotland is not part of ‘dysfunctional’ = yfuni = UNIFY) link-up (UNIFY).