Across:
1 Changes the course (SWINGS) for endless (end ‘less’ = S-) pieces of chicken (-WINGS) (SWINGS),
4 Sailor (able-bodied seaman = AB-) open to (open ‘to’ = -T-) workers (-MEN-) in Utah (U-T) (ABUTMENT) providing a supporting role on the bridge (ABUTMENT),
9 Puerto Rican dismisses Count? (‘Puerto Rican’ misses ‘count’ = perria = REPAIR) Darn! (REPAIR),
10 Praises (ACCLAIMS) a (A-) head of clan (head of ‘clan’ = -C-) from States (states/declares = -CLAIMS) (ACCLAIMS),
12 Samples (PORTFOLIO) drink (PORT-) with duck (-O-) in filo (filo = F-LIO) bake (= anagram indicator) (PORTFOLIO),
13 Cats from pit scared (‘cats’ from ‘pit scared’ = pired = PRIDE) by a group of lions (PRIDE),
14 Classy record (EXERCISE BOOK) of what one studied when working out (EXERCISE BOOK),
18 Has a job examining relative’s (FAMILY DOCTOR) bloodline (FAMILY) for Spike (spike/tamper = DOCTOR) (FAMILY DOCTOR),
21 Part of Malaga invokes (part of ‘Malaga invokes’ = aga in = AGAIN) another time (AGAIN),
22 Short oral examination (VIVA- voce) in German city (BON -N-) on the Last Judgement (last ‘judgement’ = -T) (BON VIVANT) by one who enjoys the good life (BON VIVANT),
24 Headache (MIGRAINE) for Frenchman (Monsieur = M-) travelling (= anagram indicator) Nigeria (Nigeria = -IGRAINE) (MIGRAINE),
25 Bark missing from branch-like (‘bark’ missing from ‘branch like’ = nchlie = LICHEN), mossy growth (LICHEN),
26 Hot (H-) wing (-ARM-) from takeaway (-LESS) (HARMLESS) is fairly mild (HARMLESS),
27 Casts a shadow over (SHADES) Dante’s ending (‘Dantes’ ending = S-) in The Inferno (-HADES) (SHADES).
Down:
1 For the director, adapted what’s in 17 across (for the director, adapted what’s in ‘writings’ = SCRIPTED) and did a job on the books (SCRIPTED),
2 Foreign (= anagram indicator) editor (editor = I-ORTED) welcomes British politician (-MP-) (IMPORTED) brought in from overseas (IMPORTED),
3 In retrospect (= reversal indicator), political party (Fine Gael = FG = G-F) protects most of (e) the country (‘Eire’ without ‘e’ = eir = RIE-) (GRIEF) from deep sorrow (GRIEF),
5 Put up the money (BACK) for loft (loft) at The Centre (of) (‘loft’ at the centre = OF) on the far side of (BEYOND) (BACK OF BEYOND) Timbuktu it’s said (BACK OF BEYOND),
6 Put in the picture (tell) briefly (l) (‘tell’ without ‘l’ = TEL-) with sweetheart? (‘sweet’ heart = -E-) Still (still = -PHOTO) (TELEPHOTO), that’s a long shot (TELEPHOTO lens),
7 Turns up (= reversal indicator) bug (rile = EL-IR) catches one (-I-) mystery man (-X-) (ELIXIR) offering magic potion (ELIXIR),
8 It’s a sample (TESTER) from street (street = TESTER) cook (= anagram indicator),
11 They hold everything together (ELASTIC BANDS) in flexible (ELASTIC) bar (BAN-) for 500 (-D-) on bender (-S bend) (ELASTIC BANDS),
15 Annoying series of posts (CHAIN MAIL) from one of those protecting old soldier (flexible armour of metal rings = CHAIN MAIL),
16 Has a partner (ATTACHED) working in the embassy (attaché = ATTACHE-) for US Democrat (-D) (ATTACHED),
17 Reports (WRITINGS) of woman (W-) from Rising (rising = RI-INGS) organising (= anagram indicator) around square (-T- square) (WRITINGS),
19 Whiskey (W-) blows the head off (h) Hurt (‘harm’ without ‘h’ = -ARM-) with most (e) of the (‘the’ without ‘e’ = -TH) (WARMTH) heat (WARMTH),
20 Harry (harry/harass = BADGER) isn’t good (BAD-), for example (e.g. = -GE-), recalling (= reversal indicator) arithmetic (from the 3Rs = -R) (BADGER),
23 Sample of daiquiri shaken (sample of ‘daiquiri shaken’ = iri sh = IRISH) in a manner of speaking (IRISH).