Across
Scientific solver admits he is perplexed by abbreviation of name on computer (7,5)
Force cutting signal, energy maintained (5)
Crop circles as chopped down seed (6,3)
Sultan leaves home (7)
See 19
Had thug sent suggestive signal? (10)
Work done, thus holds back (4)
Two short tools for fool (4)
12a
1917 18 across where infant lying, funny feeling justified, one certainly admits (10,7)
Channel carrying hydrogen across its length (7)
See 18 down
Feeling of great happiness about black plant (9)
Scorer has run out of play, perhaps? (5)
1995 18 across: a deception say, not up for review (5,7)
Down
Ladies and gentlemen carrying father up and down over peak in America, spotted horse (9)
Man's place in 1912 18 across, left in hole beneath one's feet (8)
Member of old empire, preserved? (5)
Sour cream offset with acid, nothing less (9)
Plant ice axe initially under murder victim (6)
Feature of Riyadh, an oil-rich capital (5)
Stick wobbly bottom in goulash, being vulgar (6)
Stoppage in force once beginning to slow (6)
Fear of novelty washer in replacement of a hip bone (9)
Girl almost taken in by trivial prediction (9)
Unruly as punks, one finally arrested comes quietly (6,2)
24a
Murder riled screws, first sign in 1983 18 across (6,7)
Country quarantining small spaniels? (3-3)
Hair and metallic mineral stink (6)
Fend off leader of pirates in film (5)
Selection of people: four originally darn trousers (5)
Type letters or click words in the clue