Doctor strives to obtain films (6)
I believe the answer is:
movies
'films' is the definition.
('movie' can be a synonym of 'film')
'doctor strives' is the wordplay.
'doctor' becomes 'mo' (medical officer).
'strives' becomes 'vies' (I've seen this in another clue).
'mo'+'vies'='MOVIES'
'to obtain' acts as a link.
(Other definitions for movies that I've seen before include "big-budget features" , "Flicks" , "Cinema films" , "Motion pictures" , "Informally, films shown in cinemas" .)