Non-believer hates it, perhaps (7)
I believe the answer is:
atheist
'non-believer' is the definition.
(someone who doesn't believe in God)
'hates it perhaps' is the wordplay.
'perhaps' is an anagram indicator.
'hates'+'it'='hatesit'
'hatesit' with letters rearranged gives 'ATHEIST'.
(Other definitions for atheist that I've seen before include "Non-believer in god - hates it (anag)" , "One denying existence of a god" , "One denies the existence of gods" , "One who has no belief in a god" , "Disbeliever in deities" .)