Eye record in match (6)
I believe the answer is:
peeper
'eye' is the definition.
(synonyms)
'record in match' is the wordplay.
'record' becomes 'ep'.
'in' means one lot of letters goes inside another.
'match' becomes 'peer' (synonyms).
'ep' placed within 'peer' is 'PEEPER'.
(Other definitions for peeper that I've seen before include "Viewer" , "Voyeur" , "Eye (slang)" .)