Sacred text of Islam (5)
I believe the answer is:
koran
'sacred text of islam' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for koran that I've seen before include "Islamic sacred book" , "Sacred Islamic writings" , "Islam's sacred book" , "Holy book of Islam" , "Sacred book of Islam with revelations of Muhammad" .)