Drive off to a film about the capital of Portugal (5)
I believe the answer is:
repel
'drive off' is the definition.
(synonyms)
'film about the capital of portugal' is the wordplay.
'film' becomes 'reel' (reel is a kind of film).
'about' means one lot of letters goes inside another.
'the capital of' indicates taking the first letters.
The first letter of 'portugal' is 'p'.
'reel' enclosing 'p' is 'REPEL'.
'to a' acts as a link.
(Other definitions for repel that I've seen before include "push off" , "Successfully resist" , "Drive back or disgust" , "Nauseate" , "Fill with distaste" .)