Flags like a doctor with a love for operations (6)
I believe the answer is:
droops
'flags' is the definition.
('droop' can be a synonym of 'flag')
'doctor with a love for operations' is the wordplay.
'doctor' becomes 'dr' (abbreviation).
'with' says to put letters next to each other.
'a love' becomes 'o' (love means zero in tennis).
'for' is a charade indicator (letters next to each other).
'operations' becomes 'ops' (abbreviation).
'dr'+'o'+'ops'='DROOPS'
'like a' is the link.
(Other definitions for droops that I've seen before include "Sags through tiredness" , "'Sags, wilts (6)'" , "Hangs limply down" , "Hangs loosely, sags" , "Grows weak and hangs down" .)