Competition cheat put on trial (7)
I believe the answer is:
contest
'competition' is the definition.
('contest' can be a synonym of 'competition')
'cheat put on trial' is the wordplay.
'cheat' becomes 'con' (con is a kind of cheat).
'put on' is a charade indicator (letters next to each other).
'trial' becomes 'test' ('test' can be a synonym of 'trial').
'con'+'test'='CONTEST'
(Other definitions for contest that I've seen before include "Competition; dispute" , "Competition or conflict" , "Match" , "Oppose - competition" , "Tournament" .)