Detestable nob, rather drunk (9)
I believe the answer is:
abhorrent
'detestable' is the definition.
('abhorrent' can be a synonym of 'detestable')
'nob rather drunk' is the wordplay.
'drunk' indicates an anagram.
'nob'+'rather'='nobrather'
'nobrather' is an anagram of 'ABHORRENT'.
(Other definitions for abhorrent that I've seen before include "Horrible" , "hateful" , "noisome" , "Disgusting, loathsome" , "execrable" .)