Inside information about literary style (5)
I believe the answer is:
genre
'literary style' is the definition.
(I've seen this before)
'inside information about' is the wordplay.
'inside information' becomes 'gen' ().
'about' becomes 're' ('re' means regarding or about).
'gen'+'re'='GENRE'
(Other definitions for genre that I've seen before include "Category of literature" , "Writing style" , "Particular style of art or literature, may be green" , "class" , "expressive style of music" .)