Wasted opening in brilliant game (6)
I believe the answer is:
blotto
'wasted opening' is the definition.
'blotto' can be an answer for 'wasted' (both can mean drunk). I am not certain of the 'opening' bit.
'in brilliant game' is the wordplay.
'in brilliant' becomes 'b' (I can't explain this - if you can you should believe this answer much more).
'game' becomes 'lotto' (lotto is a kind of game).
'b'+'lotto'='BLOTTO'
Can you help me to learn more?
(Other definitions for blotto that I've seen before include "Very drunk (informal)" , "Drunken" , "wrecked" , "As one plastered" , "To bolt away in drunk state" .)