Nervous, irritable (4)
I believe the answer is:
edgy
I believe this clue is a double definition.
'nervous' is the first definition.
(synonyms)
'irritable' is the second definition.
(edgy or on edge can mean irritable)
(Other definitions for edgy that I've seen before include "ready to flap?" , "Nervous and tense, irritable" , "In a tense state" , "Sharp in outline" , "Anxious" .)