A boxing match, more or less (5)
I believe the answer is:
about
'more or less' is the definition.
(synonyms)
'a boxing match' is the wordplay.
'boxing match' becomes 'bout' (bout can mean a boxing match).
'a'+'bout'='ABOUT'
(Other definitions for about that I've seen before include "Not exactly - concerning" , "Approximately, or in vicinity" , "Encompassing" , "nearby" , "Concerning (something)" .)