Official's never penning books (6)
I believe the answer is:
notary
'official's' is the definition.
(notary is a kind of official)
'never penning books' is the wordplay.
'never' becomes 'nary' (I've seen this before).
'penning' indicates putting letters inside.
'books' becomes 'OT' (Old Testament).
'nary' placed around 'ot' is 'NOTARY'.
(Other definitions for notary that I've seen before include "Legal clerk" , "Certifier of deeds etc." , "legal worker" , "Official legally authorised to witness signatures" , "A public one certifies documents" .)