Drunk last to sleep, finally, before day (9)
I believe the answer is:
plastered
'drunk' is the definition.
(slang term)
'last to sleep finally before day' is the wordplay.
'last to' says to take the final letters.
'finally' becomes 'last' (synonyms).
'before' becomes 'ere' (poetic term for 'before').
'day' becomes 'd' (abbreviation for day).
The last letter of 'sleep' is 'p'.
'p'+'last'+'ere'+'d'='PLASTERED'
(Other definitions for plastered that I've seen before include "Coated thickly, being slangily drunk" , "spread" , "Like member in cast" , "Drunk (slang)" , "Drunk (as a ceiling or wall may be)" .)