Lotto (5)
I believe the answer is:
bingo
'lotto' is the definition.
(I know that lotto can be written as bingo)
This is the entire clue.
(Other definitions for bingo that I've seen before include "Housey-housey" , "Game in which "two little ducks" might be called" , "Cry on discovering something" , "Number game" , "Lotto" .)