Across:
8 DUP (DUP) unsettled (= anagram indicator) (DUP = UPD-) by flipping (= reversal indicator) paramilitaries' (ETA = -ATE) (UPDATE) reform (UPDATE),
9 Strip (UNCLOTHE) of luncheon meat has no name? (‘luncheon meat’ has no ‘name’ = luncheot = UNCLOTHE),
10 Come in after everyone else (LOSE) to open 14 across (open ‘lose face’ = LOSE),
11 Religious leader (RABBI-) splits (tears = -T EARS) (RABBIT EARS) with those once employed as an aid to reception in a moving way (RABBIT EARS),
12 Task forces have no fear (‘task forces’ have no ‘fear’ = tskocs = STOCKS) of those kept back in reserve (STOCKS),
14 Ditch (LOSE) celebrity (FACE) (LOSE FACE) or suffer humiliation (LOSE FACE),
15 Get out of jail card (INSURANCE POLICY) – presumably that’s only for the one undercover with the car (INSURANCE POLICY),
18 Regardless of how (THAT SAID) politician (TD = T-D) takes in Panama (-HAT), South Africa (SA-) and Ireland (-I-) (THAT SAID),
20 One of those in the abbey (play) needing no introduction (p) (‘play’ without ‘p’ = LAY-) leads monks and nuns (leads ‘Monks And Nuns’ = -MAN) (LAYMAN) and one of the flock (LAYMAN),
22 Commissioning (APPOINTING) new (= anagram indicator) painting (painting = AP-INTING) containing river (-PO-) (APPOINTING),
24 Gave voice to (SAID) those at the end of 18 across (those at the end of ‘that said’ = SAID),
25 Heads to Catania, Rimini, Imola (heads to ‘Catania Rimini Imola’ = CRI-) and Milan (Milan) working (= anagram indicator) (Milan = -MINAL) (CRIMINAL) for The Don (CRIMINAL),
26 Ban (OUTLAW) one of those in 25 across similarly (one ‘criminal’ = OUTLAW).
Down:
1 Decide not to join (OPT OUT) old (O-) heartless (a) Irishman (Pat) ('pAt' without 'a' = -PT) going on holiday (OUT) (OPT OUT),
2 Part of the watch (FACE) at the back of 14 across (back of ‘lose face’ = FACE),
3 State (State of NEBRASKA) of new (N-) engineer (-E-) – a supporter of female (-BRA-) music synonymous with Jamaica (-SKA music) (NEBRASKA)
4 Source of light (BULB) coming from Hostelry (Bed and Breakfasts = B&B = B-B) overlooking university (University of Limerick = -UL-) (BULB),
5 Provisional certificates (SCRIPS) produced by actor at the centre (‘acTor’ at the centre = t) removed from screenplays (‘scripTs’ without ‘t’ = scrips = SCRIPS),
6 Type of plant (POWER- plant) associated with insect (fly = -F-LY) gripping university (University of Limerick = -UL-) (POWERFULLY) intensely (POWERFULLY),
7 Doctor (= anagram indicator) to chair (to chair = THORACI-) “Cold (-C) (THORACIC) of The Chest” (THORACIC),
13 Venues where you can see Brief Encounter many times (COURTROOMS) in hangouts for the barmen (COURTROOMS),
14 Briefly (k) a gambler’s need (luck) (‘luck’ without ‘k’ = LUC-) for papers (-ID papers) (LUCID) when sober (LUCID),
16 Futile (NO-HOPE-) writing (from the 3Rs = -R-) to school (-S) (NO-HOPERS) for those with no chance of achieving their grades (NO-HOPERS),
17 Roly’s partner (Roly POLY-) got (-G-OT) around central Bethlehem (central ‘bethLehem’ = -L-) (POLYGLOT) having Arabic, Aramaic, Hebrew and English, among others (POLYGLOT),
19 Stops The Sun (AWNING) article (A-) on ugly (= anagram indicator) win (win = -WNI-) – it means nothing to both sides (both sides of ‘NothinG’ = -NG) (AWNING),
21 Sending up (= reverse indicator) veneer of rock (lamina = ANIMAL) chick perhaps? (ANIMAL),
23 When not in New Delhi (‘when’ not in ‘New Delhi’ = edli = IDLE) one is not working (IDLE),
24 Poses (SITS) going around St Kitts and Nevis on the way back (= reverse indicator) (going around ‘ST kitts and nevIS’ = stis = SITS).