Retired cook admitting King James Bible was of help (7)
I believe the answer is:
availed
'was of help' is the definition.
'retired cook admitting king james bible' is the wordplay.
'retired' is a reversal indicator.
'cook' becomes 'delia' (Delia Smith).
'admitting' means one lot of letters goes inside another.
'king james bible' becomes 'av' (abbreviation for Authorised Version).
'delia' placed around 'av' is 'deliava'.
'deliava' back-to-front is 'AVAILED'.
(Other definitions for availed that I've seen before include "Used, put into service" , "Profited from" , "Used to one's advantage" , "Helped" .)