Cutting about a hard religious leader (6)
I believe the answer is:
caliph
'leader' is the definition.
(I've seen this before)
'cutting about a hard religious' is the wordplay.
'cutting' becomes 'clip' (clip is a kind of cutting).
'about' indicates putting letters inside.
'hard religious' becomes 'h' (I can't explain this - if you can you should believe this answer much more).
'clip' enclosing 'a' is 'calip'.
'calip'+'h'='CALIPH'
(Other definitions for caliph that I've seen before include "Harun al-Rashid, say" , "Historical Muslim ruler" , "Title of rulers of the Islamic world" , "Islamic leader" , "Muslim leader" .)