Irritable request to trap snake (7)
I believe the answer is:
waspish
'irritable' is the definition.
(thesaurus)
'request to trap snake' is the wordplay.
'request' becomes 'wish' (wish is a kind of request**).
'to trap' indicates putting letters inside.
'snake' becomes 'asp' (asp is a kind of snake).
'wish' enclosing 'asp' is 'WASPISH'.
(Other definitions for waspish that I've seen before include "Bad-tempered like striped stinger" , "Easily-provoked" , "irascible" , "Spiteful (with a slender waist?)" , "stingy?" .)