Worker has loud complaint (4)
I believe the answer is:
beef
'complaint' is the definition.
(beef can mean a complaint or objection)
'worker has loud' is the wordplay.
'worker' becomes 'bee' (a worker bee).
'has' means one lot of letters go next to another.
'loud' becomes 'f' (short for forte - 'loud' in music).
'bee'+'f'='BEEF'
(Other definitions for beef that I've seen before include "joint, perhaps" , "Argument" , "Complaint; strength" , "Brawn; complaint" , "Complaint; muscle" .)