“Crotchety” used to be an expression of contempt (7)
I believe the answer is:
waspish
'crotchety' is the definition.
(thesaurus)
'used to be an expression of contempt' is the wordplay.
'used to be' becomes 'was' (I've seen this before).
'an expression of contempt' becomes 'pish'.
'was'+'pish'='WASPISH'
(Other definitions for waspish that I've seen before include "'Very irritable, like a stinger (7)'" , "Bad-tempered like striped insect" , "Splenetic" , "Bad-tempered like stinging insect" , "Bad-tempered like striped stinger" .)