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