Game has Robin going to some extent (5)
I believe the answer is:
bingo
'game' is the definition.
(bingo is a kind of game)
'has robin going to some extent' is the wordplay.
'to some extent' indicates the answer is hidden within the clue.
'BINGO' can be found hidden inside 'has robin going'.
(Other definitions for bingo that I've seen before include "House!" , "Number game" , "I've completed my card!" , "Popular gambling game in which numbers are called at random" , "Housey-housey" .)