Book giving priest great joy (10)
I believe the answer is:
revelation
'book' is the definition.
(I know that Revelation is a book)
'giving priest great joy' is the wordplay.
'giving' is a charade indicator (letters next to each other).
'priest' becomes 'rev' (short for reverend).
'great joy' becomes 'elation' (I've seen this before).
'rev' put next to 'elation' is 'REVELATION'.
(Other definitions for revelation that I've seen before include "Surprising disclosure" , "The last book to give clergyman" , "telling statement" , "unexpected display" , "NT book" .)