Bad start to a game, being drunk (6)
I believe the answer is:
blotto
'being drunk' is the definition.
(slang term)
'bad start to a game' is the wordplay.
'start to' says to take the initial letters.
'a game' becomes 'lotto' (the UK National Lottery).
The first letter of 'bad' is 'b'.
'b'+'lotto'='BLOTTO'
(Other definitions for blotto that I've seen before include "As one plastered" , "Blind drunk" , "Unconscious from drink" , "Slangily drunk - ready to bolt" , "Cockeyed drunk" .)