Cultured occasionally cheat in game (6)
I believe the answer is:
cluedo
'game' is the definition.
(I know that Cluedo is a board game)
'cultured occasionally cheat' is the wordplay.
'occasionally' indicates alternate letters.
'cheat' becomes 'do'.
The alternating letters of 'cultured' are 'clue'.
'clue'+'do'='CLUEDO'
'in' acts as a link.
(Other definitions for cluedo that I've seen before include "Murder mystery board game" , "Detective game" .)