Abominable, abhorrent (7)
I believe the answer is:
heinous
This clue is a double definition.
'abominable' is the first definition.
(I've seen this in another clue)
'abhorrent' is the second definition.
(thesaurus)
(Other definitions for heinous that I've seen before include "Loathsome" , "Shocking (offence)" , "Revolting" , "Dreadful" , "Execrable" .)