Religion with Five Pillars (5)
I believe the answer is:
islam
'religion with five pillars' 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" , "Faith with five pillars" , "Mohammed's religion" , "Religion of the Koran" .)