Decline work supporting doctor (4)
I believe the answer is:
drop
'decline' is the definition.
(I've seen this before)
'work supporting doctor' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor'**).
'op' put after 'dr' is 'DROP'.
(Other definitions for drop that I've seen before include "Small bit - fall" , "Leave out of team" , "Discontinue -- delivery" , "Fall; abandon" , "Wee dram" .)