Record of a polo game (3)
I believe the answer is:
log
'record' is the definition.
(logging is a kind of recording)
'of a polo game' is the wordplay.
'of' indicates a hidden word.
'LOG' is hidden in the letters of 'polo game'.
(Other definitions for log that I've seen before include "fuel consumed" , "Formal record" , "Chunk of wood" , "Official record of events" , "Piece of wood - record" .)