Defeats -- six on the cricket field? (6)
I believe the answer is:
stumps
I believe this is a double definition.
'defeats' is the first definition.
(stump can mean to outwit or defeat)
'six on the cricket field?' is the second definition.
(six stumps across the two wickets in cricket)
(Other definitions for stumps that I've seen before include "Baffles using cricket uprights" , "The upright pieces in cricket wicket" , "The uprights in cricket wicket" , "causes confusion" , "(In cricket) close of play" .)