Wilt as doctor finds zero work (5)
I believe the answer is:
droop
'wilt' is the definition.
('droop' can be a synonym of 'wilt')
'doctor finds zero work' is the wordplay.
'doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor').
'finds' means one lot of letters go next to another.
'zero' becomes 'o'.
'work' becomes 'op' (abbreviation for opus).
'dr'+'o'+'op'='DROOP'
'as' acts as a link.
(Other definitions for droop that I've seen before include "Sag downwards" , "Decline" , "male problem?" , "sink" , "Become limp" .)