Fight to get prisoner to trial (7)
I believe the answer is:
contest
'fight' is the definition.
(thesaurus)
'get prisoner to trial' is the wordplay.
'get' says to put letters next to each other.
'prisoner' becomes 'con' (abbreviation for 'convict').
'to trial' becomes 'test' (synonyms).
'con' next to 'test' is 'CONTEST'.
'to' acts as a link.
(Other definitions for contest that I've seen before include "Competition or conflict" , "Oppose - competition" , "Tournament" , "Competition; dispute" , "Match" .)