English union in factory is easily irritated (8)
I believe the answer is:
petulant
'easily irritated' is the definition.
(I've seen this before)
'english union in factory' is the wordplay.
'english' becomes 'e' (abbreviation).
'union' becomes 'tu' (I've seen this in other clues**).
'in' is an insertion indicator.
'factory' becomes 'plant' (I've seen this before).
'e'+'tu'='etu'
'etu' put inside 'plant' is 'PETULANT'.
'is' acts as a link.
(Other definitions for petulant that I've seen before include "Fractious, peevish" , "Pouting" , "Irritable, sullen" , "Childishly sulky or bad-tempered" , "Peevish, surly" .)