Christian holy book (5)
I believe the answer is:
bible
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">christian holy book</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for bible that I've seen before include "work that's accepted" , "The Christian or Jewish scriptures" , "Book regarded as the ultimate authority on its subject" , "An authoritative text" , "It contains scriptures" .)