Across:
8 Tried (HAD A GO) to hold-up first (‘hold-up’ first = H-) bill (-AD-) from government lawyer (attorney general = -A G-) and it came to nothing (-O) (HAD A GO),
9 One of those American footballers (position in American football = RECEIVER) is on the phone (RECEIVER),
10 Some stealth aircraft (some ‘stealth aircraft’ = HAIR) tends to get clipped (HAIR),
11 Quantify (MEASURE-) for Northern political party (Democratic Unionist Party = -D UP) (MEASURED UP) what the man of the cloth did (MEASURED UP),
12 Extra (MARGIN) room to spare? (MARGIN),
14 A neighbour of 13 down from the start (start of ‘German wine’ = ‘German’ = a neighbour of AUSTRIAN) in Australia (AU-) running (= anagram indicator) trains (trains = -STRIAN) (AUSTRIAN),
15 Refers to an extremely precarious situation (SWORD OF DAMOCLES) that’s in suspension and only a hair’s breath away? (SWORD OF DAMOCLES suspended by a single hair over his head),
18 Faithful subject (LOYALIST) out (= anagram indicator) to …? I’ll say! (to I’ll say = LOYALIST),
20 Conservatism is terrified internally (‘conservatism is terrified’ internally = MISTER) by address (MISTER),
22 Dragged one’s feet (SLOWED DOWN) in Northern Ireland (DOWN) after (= positional indicator) momentum was lost (SLOWED) (SLOWED DOWN),
24 Poses (SITS) with strategists dismissing targets (‘strategists’ dismissing ‘targets’ = ists = SITS),
25 Turn a blind eye without Beryl (‘turn a blind eye’ without ‘Beryl’ = tunainde = INUNDATE) Flood (flood/overwhelm = INUNDATE),
26 Boxer (pub) loses the head (p) (‘pup’ without ‘p’ = UP-) with half of those in 25 across (half of ‘inundate’ = -DATE) (UPDATE) – is that correct? (UPDATE).
Down:
1 A (-A-) new (-N-) bill (-AD-) in California (C-A) (CANADA) refers to state over the American border (CANADA),
2 Just (FAIR) afraid to drop ad (‘afraid’ to drop ‘ad’ = frai = FAIR),
3 College (C-) at the end of term (end of ‘term’ = -M-) in Arabian country (Oman = -OM-AN-) has party (-DO) (COMMANDO) for one going on The Missions (COMMANDO),
4 Operatic song (ARIA) from familiar film is missing (from “familiar” “film” is missing = “familiar” without “film” = aiar = ARIA),
5 It crops up (OCCURS) with wild (= anagram indicator) crocus (crocus = OCCURS),
6 What those having a laugh are capable of (WISE CRACKS) with sage (WISE) and head of cauliflower (head of ‘cauliflower’ = C-) in place of ginger (spice rack = -RACK-) at school (-S) (WISE CRACKS),
7 Keep tabs on (REGULATE) police (police/control = REGULATE),
13 European (GERMAN) from Bordeaux (WINE) (GERMAN WINE) is drunk in the Mosel (GERMAN WINE),
14 Custodian releasing cons (‘custodian’ releasing ‘cons’ = utdia = AUDIT) – it’s every tax-payers worry (AUDIT),
16 Try to win (WOO-) with Dublin (-D-), Limerick (-L-) as well as (-AND) (WOODLAND) Nottingham Forest (WOODLAND),
17 Drive (MOMENTUM) relative (M-UM) to get hold of fake (= anagram indicator) Monet (Monet = -OMENT-) (MOMENTUM),
19 Raises (= reversal indicator) donations (aid = -DIA-) in pub (IN-N) (INDIAN) dinner (INDIAN),
21 Grounds (ESTATE) for English (E-) to say it (-STATE) (ESTATE),
23 Frank (OPEN) is in part of Copenhagen (is in part of ‘Copenhagen’ = OPEN),
24 Toff leaves fast food (‘Toff’ leaves ‘fast food’ = asod = SODA) and drink (SODA).