Irritable match ending in acrimony (5)
I believe the answer is:
testy
'irritable' is the definition.
(testy can mean irritable or annoyed)
'match ending in acrimony' is the wordplay.
'match' becomes 'test' (test match is a kind of match).
'ending in' indicates one should take the final letters.
The last letter of 'acrimony' is 'y'.
'test'+'y'='TESTY'
(Other definitions for testy that I've seen before include "Grumpy" , "Bad-tempered" , "Showing irritation" , "bad temper" , "Cross" .)