Perfect example in eastern religious book (7)
I believe the answer is:
epitome
'perfect example' is the definition.
(the epitome of a thing is a perfect example of it)
'eastern religious book' is the wordplay.
'eastern' becomes 'e'.
'religious' becomes 'pi' (british abbreviation for pious).
'book' becomes 'tome' (a tome is a book).
'e'+'pi'+'tome'='EPITOME'
'in' acts as a link.
(Other definitions for epitome that I've seen before include "Model" , "Embodiment or perfect example" , "Something embodying perfectly a stated quality or idea" , "Digest" , "Summary; embodiment" .)