Story books, genius (6)
I believe the answer is:
talent
'genius' is the definition.
(genius can mean someone's talent at something)
'story books' is the wordplay.
'story' becomes 'tale' (synonyms).
'books' becomes 'NT' (abbreviation for New Testament).
'tale'+'nt'='TALENT'
(Other definitions for talent that I've seen before include "Special or very great ability" , "Natural ability or flair" , "Attractive people" , "Natural ability for some activity" , "money no longer usable" .)