Chief to bring in a book (9)
I believe the answer is:
important
'chief' is the definition.
(similar in meaning)
'bring in a book' is the wordplay.
'bring in' becomes 'import' (bring in to a country).
'book' becomes 'nt' (New Testament).
'import'+'a'+'nt'='IMPORTANT'
'to' is the link.
(Other definitions for important that I've seen before include "material" , "Eminent" , "Noted" , "Significant, valuable" , "It's vital" .)