Irritable jury's conclusion after trial (5)
I believe the answer is:
testy
'irritable' is the definition.
(testy can mean irritable or annoyed)
'jury's conclusion after trial' is the wordplay.
'conclusion' suggests the final letters.
'after' means one lot of letters go next to another.
'trial' becomes 'test' (synonyms).
The last letter of 'jury' is 'y'.
'y' put after 'test' is 'TESTY'.
(Other definitions for testy that I've seen before include "snappy" , "likely to flare up?" , "Easily irritated" , "Ratty" , "Irascible" .)