A competition, as opposed to a match (7)
I believe the answer is:
contest
'a competition' is the definition.
(synonyms)
'opposed to a match' is the wordplay.
'opposed to' becomes 'con' (as in pros and cons).
'a match' becomes 'test' (as in a test match in cricket).
'con'+'test'='CONTEST'
'as' acts as a link.
(Other definitions for contest that I've seen before include "Competition; dispute" , "Competition or conflict" , "Oppose - competition" , "Tournament" , "Match" .)