Opponent erroneously holding record (5)
I believe the answer is:
enter
'record' is the definition.
('enter' can be a synonym of 'record')
'opponent erroneously holding' is the wordplay.
'holding' indicates the answer is hidden within the clue.
'ENTER' is hidden within 'opponent erroneously'.
(Other definitions for enter that I've seen before include "Make a record of" , "Get in" , "cross the threshold" , "Fill in" , "Come in - penetrate - record" .)