Doctor round surgery to wilt (5)
I believe the answer is:
droop
'wilt' is the definition.
('droop' can be a synonym of 'wilt')
'doctor round surgery' is the wordplay.
'doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor').
'round' becomes 'o' (round can mean a round object).
'surgery' becomes 'op' (short for operation).
'dr'+'o'+'op'='DROOP'
'to' acts as a link.
(Other definitions for droop that I've seen before include "Decline" , "Dangle" , "Become limp" , "Go limp" , "sink" .)