Rival church leader's hint in article? Not at all (8)
I believe the answer is:
antipope
'rival church leader's' is the definition.
(I've seen this before)
'not at all' is the wordplay.
'not' becomes 'anti' (I've seen this in other clues).
'at all' becomes 'pope' (I can't explain this - if you can you should believe this answer much more).
'anti'+'pope'='ANTIPOPE'
'hint in article?' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for antipope that I've seen before include "Breakaway religious leader" , "Rival church leader" , "Not so holy father" , "man challenging religious authority" , "rogue cleric" .)