Across:
1 Stabilises off site (‘stabilises’ off ‘site’ = abilss = BASILS) or in the allotment (BASILS),
4 Scout Kit (Scout kit = STICK OUT) produced (= anagram indicator) by Project (project/extend = STICK OUT),
9 Swinger’s warning (warning on golf course = ‘fore’ = F-ORE) about old city (-UR-) (FURORE) commotion (FURORE),
10 Times can (times can = SEMANTIC) change (= anagram indicator) the meaning of words (SEMANTIC),
12 Most of the (s) fees (‘costs’ without ‘s’ = COST-) for joining a (-A) registered (R-) Women’s Institute (Irish Countrywomen’s Association = -ICA) (COSTA RICA) in Central America (COSTA RICA),
13 Lookers-on dismiss Oslo (‘lookers-on’ dismiss ‘Oslo’ = keron = KRONE) – the Norwegian capital (capital/money = KRONE),
14 They recognise a good yarn when they hear it (LIE DETECTORS) ignoring the veracity of the facts (LIE DETECTORS),
18 Irish writer (BRENDAN BEHAN) is losing the head (t) on trend (‘trend’ without ‘t’ = REND -) for leaders of a nasty business entertaining hoods (leaders of ‘a nasty business entertaining hoods’ = AN BEH-) in Prohibition (B-AN) (BRENDAN BEHAN),
21 Sounds like (= homophone indicator) a film (a film = “a veil” = “avail” = AVAIL) to take advantage of perhaps (AVAIL),
22 It’s a long story (SAGA-) getting caught (-C-) with debts (IOUs = -IOUS) (SAGACIOUS) showing all the hallmarks of a wise guy (SAGACIOUS),
24 Got a job at a club (SIGNED) that’s popular (IN) (SIGNED IN) and on arrival did this for receptionist (SIGNED IN),
25 Dean leaves broad beans (‘Dean’ leaves ‘broad beans’ = broabs = ABSORB) to soak (ABSORB),
26 Wine (Rosé = ROSE-) tasting initially (‘tasting’ initially = -T-) set- (set = -TES) -up (= reversal indicator) (ROSETTES) for those taking places at the Horse Show (ROSETTES),
27 A Celt’s (a Celts = CASTLE) building (= anagram indicator) in Dungannon owned by Hugh O’Neill (Dungannon CASTLE – the seat of Hugh O’Neill).
Down:
1 Make up (fib) most of the story (f) (‘fib’ without ‘f’ = ib = BI-) about (= reversal indicator) conversation pieces in the Gaeltacht (Gaeltacht/Irish ‘words’ = -FOCALS) (BIFOCALS) and those seeing things (BIFOCALS),
2 It must be said time and time again (STRESSED), this has already been highlighted (STRESSED),
3 Grub (LARVA) from the foreign (the = LA-) holiday camper (recreational vehicle = -RV-) is key (music key -A) (LARVA),
5 Most of them (most of ‘them’ = THE) go the distance (LAST) with most of 20 down (most of ‘laughs’ = LAUGH) (THE LAST LAUGH) – succeeding when others thought they failed – Ha! (THE LAST LAUGH),
6 Damage part of the cage holding the bones (CRACK A RIB) of cocaine (CRACK cocaine) found on American (A) boat (RIB) (CRACK A RIB),
7 Best (OUTFOX) produced tofu (tofu = OUTF-) salad (= anagram indicator) to go with beef (-OX) (OUTFOX),
8 No lairds in Lake District (no ‘lairds’ in ‘Lake District’ = ketict = TICKET) will give access to concert (TICKET),
11 Be patient (BIDE ONE’S TIME) – might do this in the waiting room for a favourable outcome (BIDE ONE’S TIME),
15 Small measure (small measurement = EN-) of musty (= anagram indicator) Merlot (Merlot = - ROLME-T) around the end of function? (end of the ‘function’ = -N-) (ENROLMENT) That’s some admission! (ENROLMENT),
16 Take a photo (SHOOT) on holiday (OUT) (SHOOT-OUT) of what some cowboys came up with to settle an argument (SHOOT-OUT),
17 Ulster (U-) bus lane (bus lane = -NUSABLE) (UNUSABLE) potentially is not fit for purpose (UNUSABLE),
19 Free (= anagram indicator) Press – a (press a = PASSER) type that’ll get the ball rolling (footballer/ PASSER gets the ball rolling),
20 Shows one’s amusement (LAUGHS) leading to the foreign (the = LA-) expressions of disgust (-UGHS) (LAUGHS),
23 A charmed sort is mesmerized (COBRA is hypnotised/mesmerized in snake charming) by what’s found in Art Deco bracelet (COBRA is found in ‘art deco bracelet’).