Game of chance - fate as well? Not entirely (5)
I believe the answer is:
'game of chance' is the definition.
(I've seen this before)
'fate as well? not entirely' is the wordplay.
'fate' becomes 'lot' ('lot' can be a synonym of 'fate').
'as well?' becomes 'too' ('too' can be a synonym of 'as well').
'not entirely' means to remove the last letter.
'too' with its last letter taken off is 'to'.
(Other definitions for lotto that I've seen before include "Bingo - Venetian painter" , "Game of chance similar to bingo" , "Game of chance based on numbered balls being drawn at random" , "house" , "Lucky draw" .)