Knack revealed in story books (6)
I believe the answer is:
talent
'knack' is the definition.
(I've seen this in another clue)
'story books' is the wordplay.
'story' becomes 'tale' (synonyms).
'books' becomes 'NT' (New Testament).
'tale'+'nt'='TALENT'
'revealed in' acts as a link.
(Other definitions for talent that I've seen before include "Natural ability or quality" , "money no longer usable" , "ancient coin" , "Inborn ability or facility" , "Flair, aptitude" .)