British bile about book (5)
I believe the answer is:
bible
'book' is the definition.
(bible is a kind of book)
'british bile about' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in BBC).
'about' indicates putting letters inside.
'b' inserted inside 'bile' is 'BIBLE'.
(Other definitions for bible that I've seen before include "The Good Book" , "An authoritative text" , "Christian holy book" , "Holy Scripture" , "Holy books" .)