Leader in a mosque (4)
I believe the answer is:
imam
'leader in a mosque' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for imam that I've seen before include "Ma, I'm off to find religious Muslim" , "Mosque's prayer leader" , "Accompaniment in baroque music" , "Person leading devotions in a mosque" , "Islamic religious leader" .)