Irritable, quarrelsome (5)
I believe the answer is:
testy
I believe this clue is a double definition.
'irritable' is the first definition.
(testy can mean irritable or annoyed)
'quarrelsome' is the second definition.
(thesaurus)
(Other definitions for testy that I've seen before include "likely to flare up?" , "Irascible" , "Bad-tempered" , "Showing irritation" , "Irritably impatient" .)