Forces doctor to struggle to get the picture (5)
I believe the answer is:
movie
'the picture' is the definition.
('movie' can be a synonym of 'picture')
'forces doctor to struggle' is the wordplay.
'forces doctor' becomes 'mo' (medical officer in armed forces).
'to struggle' becomes 'vie' (I've seen this before).
'mo'+'vie'='MOVIE'
'to get' acts as a link.
(Other definitions for movie that I've seen before include "Flick" , "Cinema production" , "Cinema film (mainly US)" , "provide entertainment" , "one screened" .)