Lotto variant (4)
I believe the answer is:
keno
'lotto variant' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for keno that I've seen before include "A bingo-like game" , "gambler's choice" , "2 8 [CASINO GAME]" , "gambling game" , "game of chance" .)