Loathing element - not sulphur (5)
I believe the answer is:
odium
'loathing' is the definition.
(synonyms)
'element not sulphur' is the wordplay.
I cannot really understand how this works, but
'element' could be 'u' (U is an example) and 'u' is found in the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
The remaining letters 'dim' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for odium that I've seen before include "Widespread hatred or abhorrence (5)" , "Offensiveness" , "Widespread dislike and disapproval" , "Widespread contempt or hatred" , "Dislike of someone, or something hated" .)