Action film doctor's got into (6)
I believe the answer is:
combat
'action' is the definition.
(combat is a kind of action)
'film doctor's got into' is the wordplay.
'film' becomes 'coat' (I've seen this in other clues**).
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus).
'got into' is an insertion indicator.
'coat' placed around 'mb' is 'COMBAT'.
(Other definitions for combat that I've seen before include "War; contest" , "Battle, warfare" , "sort of jacket" , "Fight or contest, may be mortal" , "type of jacket" .)