Game - Go - sure is confusing (6)
I believe the answer is:
grouse
'game' is the definition.
(I know that grouse is a type of game bird)
'go sure is confusing' is the wordplay.
'is confusing' indicates anagramming the letters.
'go'+'sure'='gosure'
'gosure' with letters rearranged gives 'GROUSE'.
(Other definitions for grouse that I've seen before include "See game bird" , "Plump game bird" , "Complain like game bird" , "Grumble; game bird" , "Grumble like game-bird" .)