Quick to get irritable (6)
I believe the answer is:
snappy
I believe this clue is a double definition.
'quick' is the first definition.
(thesaurus)
'irritable' is the second definition.
(thesaurus)
'to get' is the link.
(Other definitions for snappy that I've seen before include "Irritable, curt; stylish" , "Informally brisk" , "Irritably abrupt" , "Cleverly concise; stylish" , "Apt to speak irritably: smart and fashionable" .)