Across:
8 Business (CUSTOM) practice? (CUSTOM),
9 Looked for (SEARCHED) a (-A-) church (Roman Catholic = -RC-) hothead (‘Hot’ head = -H-) in Genesis (SE-ED) (SEARCHED),
10 Both sides of the Polish Corridor (both sides of the ‘POlish CorridOR’ = POOR) is short of money (POOR),
11 Arrested in (arrested in = RESTRAINED) disturbance (= anagram indicator) and put in chains (RESTRAINED),
12 From the start, barrister (from the start ‘Barrister’ = -B-) in court case (TRI-AL) (TRIBAL) is sticking with his own lot (TRIBAL),
14 Those enlisted (SOLDIERS) in the pay of a major employer (SOLDIERS),
15 You’d hope those in 14 across will do this (you’d hope ‘soldiers’ will PUT UP A GOOD FIGHT), and the boxing promoter should be able to manage it (PUT UP A GOOD FIGHT),
18 What you should get from 7 down (FINDINGS from ‘research’) or from investigator’s conclusions (FINDINGS),
20 The stumbling blocks (ISSUES) for lots of children (ISSUES),
22 Starter (COURSE-) at function (-WORK) (COURSEWORK) could be practical for classy types (COURSEWORK),
24 Hitting one’s stride going around (‘HItting one’s striDE’ going around = HIDE) in leather (HIDE),
25 One (I-) rigs (= anagram indicator) climb (climb = -MB-CIL-) around summit of Everest (summit of ‘Everest’ = -E-) with engineer (-E) (IMBECILE) acting foolish (IMBECILE),
26 Síle (sile = -ELIS-) gets up (= reversal indicator) after (= position indicator) writing (from the 3Rs = R-) to hotel (-H) (RELISH) with gusto (RELISH).
Down:
1 Wit (HUMOUR) seems to be missing from summer house (‘seems’ to be missing from ‘summer house’ = umrhou = HUMOUR),
2 Psychiatrists dismiss physicist (‘psychiatrists’ dismiss ‘physicist’ = atrs = STAR) in The Sun (STAR),
3 Handy personal cover (UMBRELLA) is something to put away for a rainy day (UMBRELLA),
4 Contemplates (muses) losing the head (m) (‘muses’ without ‘m’ = USES) with exercises (USES),
5 A crude container (BARREL of crude oil) taking in a lot of Bordeaux (BARREL),
6 Cite a visit (cite a visit = ACTIVITIES) planned (= anagram indicator) with things to do (ACTIVITIES),
7 Groundwork (RESEARCH) for showing off (= anagram indicator) cars here (cars here = RESEARCH),
13 The outer limits (BOUNDARIES) of spring (BOUND-) and the first sign of spring? (-ARIES) (BOUNDARIES),
14 Heavy old wool tops (‘Heavy Old Wool’ tops = -HOW-) in ship (S-S) (SHOWS) manifests (SHOWS),
16 Outfits (UNIFORMS) inform (inform = -NIFORM-) criminal (= anagram indicator) in America (U-S) (UNIFORMS),
17 Those on the water, for example (DRINKERS), capable of depleting spirits (DRINKERS),
19 Sick (= anagram indicator) note (note = NOET-) for one (-I-) with cold (-C) (NOETIC) relating to one’s head (NOETIC),
21 The first issue (ELDEST) for Adam (ELDEST),
23 Frank (OPEN) Christian from container ship (‘Christian’ from ‘container ship’ = onep = OPEN),
24 Wine from New Delhi (‘wine’ from ‘New Delhi’ = delh = HELD) kept under lock and key (HELD).