Discontinue giving a doctor work (4)
I believe the answer is:
drop
'discontinue' is the definition.
(dropping is a kind of discontinuing)
'giving a doctor work' is the wordplay.
'giving' means one lot of letters go next to another.
'a doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor'**).
'work' becomes 'op' (abbreviation for opus).
'dr'+'op' is 'DROP'.
(Other definitions for drop that I've seen before include "Small drink" , "Sink; sweet; set down" , "Finish with" , "down, say, casually" , "Discontinue; sink" .)