Fellow left work a failure (4)
I believe the answer is:
flop
'a failure' is the definition.
(flop is a kind of failure)
'fellow left work' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'left' becomes 'l' (common abbreviation).
'work' becomes 'op' (abbreviation for opus).
'f'+'l'+'op'='FLOP'
(Other definitions for flop that I've seen before include "No success" , "Fail" , "Failure - loll" , "Complete failure" , "Utter failure" .)