Film instant before contest (5)
I believe the answer is:
movie
'film' is the definition.
(synonyms)
'instant before contest' is the wordplay.
'instant' becomes 'mo'.
'before' says to put letters next to each other.
'contest' becomes 'vie' (both can mean to rival or fight).
'mo'+'vie'='MOVIE'
(Other definitions for movie that I've seen before include "picture" , "one screened" , "Gladiator for one" , "Flick" , "Cinema production" .)