A demon a bit naughty is loathed (10)
I believe the answer is:
abominated
'loathed' is the definition.
('abominate' can be a synonym of 'loathe')
'a demon a bit naughty' is the wordplay.
'naughty' indicates an anagram.
'demon'+'a'+'bit'='demonabit'
'demonabit' with letters rearranged gives 'bominated'.
'a'+'bominated'='ABOMINATED'
'is' is the link.
(Other definitions for abominated that I've seen before include "couldn't stand" , "Regarded with disgust" .)