Koranic faith (5)
I believe the answer is:
islam
'koranic faith' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for islam that I've seen before include "Mails to Muslim religion" , "Mails to great eastern religion" , "Religion based on teachings of Muhammad" , "Koran its scripture" , "Adherents of a religion" .)