Proust drunk to the state of unconsciousness (6)
I believe the answer is:
stupor
'the state of unconsciousness' is the definition.
(I've seen this before)
'proust drunk' is the wordplay.
'drunk' is an anagram indicator.
'proust' is an anagram of 'STUPOR'.
'to' acts as a link.
(Other definitions for stupor that I've seen before include "Dazed condition as from drink or drugs" , "State of being stunned" , "numbness" , "state of somnolence" , "State of shock" .)