In polo games, a record (3)
I believe the answer is:
log
'record' is the definition.
(logging is a kind of recording)
'in polo games a' is the wordplay.
'in' indicates the answer is hidden within the clue.
'LOG' is hidden in the letters of 'polo games a'.
(Other definitions for log that I've seen before include "Listing" , "Register" , "Bulky piece of wood" , "Written account of a voyage" , "Record; cut wood" .)