Green’s Dictionary of Slang

clap v.2

[SE clap, to strike a hard surface]
(W.I. Rasta)

1. to shoot.

[US]N. De Mille Smack Man (1991) 19: I could clap you with my fucking puppy in the right here and now. His puppy was the long barrell .45 [...] To clap was to shoot.
Chief Keef ‘Savage’ 🎵 My young boys clap heat / [...] / They shootin’ shit on site .
Perm ‘What’s all the talk about’ 🎵 Free S that nigga was a clappaholic / Any talk no problem he clapping on it.
[UK]T. Thorne (ed.) ‘Drill Slang Glossary’ at Forensic Linguistic Databank 🌐 Clap– attack, shoot.

2. (UK black/gang) to steal drugs.

[UK]T. Thorne (ed.) ‘Drill Slang Glossary’ at Forensic Linguistic Databank 🌐 Clap– steal drugs.

SE in slang uses

In phrases

clap back (v.)

(UK black) to respond (aggressively).

[UK]T. Thorne (ed.) ‘Drill Slang Glossary’ at Forensic Linguistic Databank 🌐 Clap back– retort, make an aggressive reply or response.
B. McQuade Attack from Within 224: Chief Justice John G. Roberts Jr. [issued] a public rebuke [...] Trump clapped back in a series of posts on Twitter.
clap in (v.) [SE clap (of thunder); i.e. the energy of one’s arrival/departure]

to rush in vigorously, to push oneself forward, to arrive or leave in a decisive manner.

[UK]Marvell Rehearsal Transpos’d 63: Hearing of a vacancy with a Noble man, he clapp’d in, and easily obtained to be his Chaplain.
Defoe Further Adventures of Robinson Crusoe 115: To take the advantage and clap in between them and their boats.
clap on (v.) [ext. SE clap on, to place with promptness and effect]

to commit oneself, to make a determined effort.

[UK]Punch 31 Jan. 80/2: And you’ll have to do no end of clapping on, I’m sure.