Hateful, earthborn eccentric (9)
I believe the answer is:
abhorrent
'hateful' is the definition.
(thesaurus)
'earthborn eccentric' is the wordplay.
'eccentric' indicates an anagram.
'earthborn' with letters rearranged gives 'ABHORRENT'.
(Other definitions for abhorrent that I've seen before include "noisome" , "Ugly" , "Detestable, really off-putting" , "Earthborn (anag) - detestable" , "Detestable, loathsome" .)