Decline the drab job in the end (3)
I believe the answer is:
ebb
'decline' is the definition.
(I know that ebb is a type of decline)
'the drab job in the end' is the wordplay.
'in the end' indicates one should take the final letters.
The final letters of 'the drab job' are 'EBB'.
(Other definitions for ebb that I've seen before include "(Of tidewater) recede" , "Type of tide" , "Tidal outflow" , "(Water) recede" , "Initially Mrs Browning's" .)