Drunk used to no purpose (6)
I believe the answer is:
wasted
I believe this clue is a double definition.
'drunk' is the first definition.
(I've seen this before)
'used to no purpose' is the second definition.
(I've seen this before)
(Other definitions for wasted that I've seen before include "Drunk (as a missed opportunity?)" , "Blown" , "Squandered or weakened" , "Frittered away" , "Dissipated; atrophied" .)