Butler finally leaves tavern drunk (7)
I believe the answer is:
servant
'butler' is the definition.
(thesaurus)
'finally leaves tavern drunk' is the wordplay.
'finally' says to take the final letters.
'drunk' indicates an anagram.
The final letter of 'leaves' is 's'.
'tavern' is an anagram of 'ervant'.
's'+'ervant'='SERVANT'
(Other definitions for servant that I've seen before include "'Flunky, lackey (7)'" , "Butler, e.g." , "One in domestic service" , "Helper or attendant (sometimes humble or obedient?)" , "Menial" .)