Across:
1 Calm down (SUBDUE), there’s a boat (SUB-) on the way (-DUE) (SUBDUE),
4 Is capable of changing (ADAPTIVE) and playing (= anagram indicator) diva tape (diva tape = ADAPTIVE),
9 Centre of attention (centre of ‘atteNtion’ = -N-) in red-hot (fiery = FI-ERY) (FINERY) Sunday best! (FINERY),
10 Fool (IMBECILE) of doctor (-MB-) finds vermin (lice) back (= reversal indicator) (lice = -ECIL-) in Ireland (.ie = I-E) (IMBECILE),
12 Byrne (Byrne) on the radio (= homophone indicator) (‘Byrne’ = ‘burn’ = CHAR-) to interrogate local (interrogate ‘local’ = -GRILL) (CHARGRILL) cook (CHARGRILL),
13 Canal (DUC-T) flowing around area (-A-) (DUCAT) in old capital (old capital/money = DUCAT),
14 Ram (PRESS) shearing (CUTTING) (PRESS CUTTING) article taken from paper (PRESS CUTTING),
18 Looks presenter in the eye (TELEPROMPTER) for putting words in the mouth of broadcaster (TELEPROMPTER),
21 Incompetent (INEPT) writer (pen) backs (= reverse indicator) (pen = -NEP-) into it (I-T) (INEPT),
22 Sidney (-SID-) follows (= position indicator) what’s trending (IN-) and outstanding (IOUs = -IOUS) (INSIDIOUS) from Machiavellian type (INSIDIOUS),
24 Deliberately concealed (ULTERIOR) there’s no initial sense (initial ‘Sense’ = ‘s’) in Ulster- (‘Ulster’ without ‘s’ = ULTER-) -Irish (-I-) alternative (-OR-) (ULTERIOR),
25 Follower (MINION) of Iron Maiden loses dare (‘Iron Maiden’ loses ‘dare’ = ionmin = MINION),
26 Hurry through (EXPEDITE) exercise (-PE-) for director (-D-) in Gate (gate = EX-IT-) finale – it’s the ultimate (‘finalE’ it’s the ultimate = -E) (EXPEDITE),
27 It’s about (RE-) what the secretary will do (-TYPE) (RETYPE) to confirm a password (RETYPE).
Down:
1 It’s not hard (it’s SOFT) to find policeman (COP-) from The Yard (-Y) (SOFT COPY) and that won’t appear in print (SOFT COPY),
2 Covers up the wounds (BANDAGES) in groups (BAND-S) over the 1960s, for instance (-AGE-) (BANDAGES),
3 Strip down (UNRIG) parts of shotgun? Right! (parts of ‘shotgUN RIGht’ = UNRIG),
5 Leave quarters (DEMILITARISE) to most of (y) the general staff perhaps (‘military’ without ‘y’ = -MILITAR-) in Waterford (Waterford/The Déise = DE-ISE) (DEMILITARISE),
6 Dump nosey (dump nosey) model (= anagram indicator) (dump nosey = PSEUDONYM) making a new name for herself (PSEUDONYM),
7 Nearly (t) fool (‘idiot’ without ‘t’ = IDIO-) heartless (heartless/remove centre = ‘r’) Bellow (‘cry’ without ‘r’ = -CY) (IDIOCY) by acting stupid (IDIOCY),
8 Tries hard (EXERTS) for specialists (experts) dismissing pressure (p) (‘experts’ without ‘p’ = EXERTS),
11 19 down (‘figure’ = FIGURE-) from institute (Dublin Institute of Technology = DIT = -D IT) on holiday (OUT) (FIGURED IT OUT) found answers (FIGURED IT OUT),
15 Protected (SHELTERED) the elders (the elders) all over the place (= anagram indicator) (the elders = SHELTERED),
16 It’s an outrage (ATROCITY) starting off from (a) main artery (‘aorta’ without ‘a’ = orta) going up (= reversal indicator) (orta = ATRO-) to Dublin, for example (-CITY) (ATROCITY),
17 Sounds like (= homophone indicator) something Santa would give (‘presents’ = ‘PRESENCE’) to the ghost of Christmas past presumably? (PRESENCE),
19 Diagram (FIGURE) of plans from Persian Gulf (‘plans’ from ‘Persian Gulf’ = eriguf = FIGURE),
20 Kept in check (PENT-UP) by writer (PEN-) knocking back (= reverse indicator) local plonk (local ‘plonk’ = put = -T-UP) (PENT-UP),
23 Advertised without dates (‘advertised’ without ‘dates’ = verid = DRIVE) for excursion (DRIVE).