Across:
8 It's not just (it's UNFAIR) one-sided? (UNFAIR),
9 Relation (relation) travelling (= anagram indicator) (relation = ORIENTAL) from the east (ORIENTAL),
10 Dropped (FELL) portion of ratatouille? Footman recoiled! (= reverse indicator) (portion of ‘ratatouiLLE Footman’ = llef = FELL),
11 What’s it locally (‘what’s it’ locally = thing = TH- -ING) about bank? (Allied Irish Banks = AIB = -AI B-) It’s got nothing (-O-) that’s wrong (-X-) (THAI BOXING) for martial arts sportspeople (THAI BOXING),
12 Stepmother lets off shot (‘stepmother’ lets off/without ‘shot’ = tepmer = TEMPER) in fit of rage (TEMPER),
14 Pointlessly (FUTILELY), in the odd feud (the odd ‘FeUd’ = FU-) lit (lit) up (= reverse indicator) (lit = -TIL-) place in Dublin (-ELY Place) (FUTILELY),
15 One of those in the house (one of those in The House/Dáil = PARLIAMENTARIAN) synonymous with a diet? (synonymous with diet/assembly = PARLIAMENTARIAN),
18 Pride, etc., (pride etc) generated (= anagram indicator) (pride etc = DECREPIT) over The Hill? (over the hill/ worn out = DECREPIT),
20 Bitter type from kitchen garden (ENDIVE) envied (envied) cook (= anagram indicator) (envied = ENDIVE),
22 Contemptuous (DISMISSIVE) of tips demonstrated in standard (tips ‘Demonstrated In Standard’ = DIS-) letter (-MISSIVE) (DISMISSIVE),
24 Extremes of Security Council (extremes of ‘SEcurity councIL’ = seil) bringing up (= reverse indicator) (seil = LIES) statements that aren’t true (LIES),
25 One is not out to expose (DISGUISE) the cover-up? (DISGUISE),
26 Winds up (CLOSES) sales force having no fear (‘sales force’ having no ‘fear’ = slesol = CLOSES).
Down:
1 A (A-) new (-N-) adjacent (next) short (t) ('next' without 't' = -NEX-) entrance leading ('Entrance' leading = -E) (ANNEXE) to wing (ANNEXE),
2 Provides work for 15 across (DÁIL provides work for ‘parliamentarian’) laid (laid) off (= anagram indicator)? (laid = DAIL),
3 Canons (canons/principles = CRITERIA) caught (C-) ceremony (-RITE-) at academy (Royal Irish Academy = -RIA) (CRITERIA),
4 Characters in photo galvanised (characters in ‘phoTO GAlvanised’ = TOGA) by what outfitters in Rome produced a long time ago (TOGA),
5 It (it) backfired (= reversal indicator) (it = TI-) on the British leaders (‘The British’ leaders = -TB-) and it (-IT) (TITBIT) is reported in the gossip column (TITBIT)
6 Organisation (United Nations organisation = UN-) carried out investigation (-EXPLORED) (UNEXPLORED) for Mariana Trench, for example, for the most part (a big part of Mariana Trench is UNEXPLORED),
7 Returning (= reverse indicator) train (aim = M-IA) contains drawn-out (long = -GNOL-) area (-A-) (MAGNOLIA) for tree with showy flowers (MAGNOLIA),
13 Crusader (PILGRIM-) lawyer (Attorney General = -AG-) from Spain (-E) (PILGRIMAGE) is presumably going to knock? (PILGRIMAGE is going to Knock shrine),
14 Paper (Financial Times = F-T) covers backstroke (= reversal indicator) swimmer (eel) (eel = -LEE-) (FLEET) going overseas to meet rivals (FLEET),
16 Drink (APERITIF) for pirate (pirate) travelling (= anagram indicator) (pirate = APERIT-) to island (-I-) on top of flagship (top of ‘Flagship’ = -F) (APERITIF),
17 Fish (Tench = T -ENCH) found around Howth Head (‘Howth head’ = -H-) and Belgium (BE) raised (= reverse indicator) (BE = -EB-) (THE BENCH) from reserves (THE BENCH),
19 Institute (-I-) in Split (split) developing (= anagram indicator) (split = P-STIL) (PISTIL) part of flower (PISTIL),
21 Caught sight of (VIEWED) for philosophy (VIEW-) writer (-ED) (VIEWED),
23 How is this on the agenda (ITEM) to take the peas out of meat pies? (take the ‘peas’ out of ‘meat pies’= meti = ITEM),
24 Gent’s (gents = LOO-) weekend (‘weeK’ end = -K) (LOOK) with Peer (LOOK).