Unpopular worker (4)
I believe the answer is:
scab
'unpopular worker' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for scab that I've seen before include "Wound's crust" , "Someone who works during a strike" , "Blackleg (colloq.)" , "He's not out" , "Ignorer of strike" .)