Medic removing tip of tail from fish (7)
I believe the answer is:
surgeon
'medic' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
(Other definitions for surgeon that I've seen before include "Medical specialist" , "one used to working in the theatre" , "Doctor in operating theatre - RN doctor" , "Hospital worker" , "Theatre worker" .)