Upcoming book -- this writer's controversial (7)
I believe the answer is:
emotive
'controversial' is the definition.
(I've seen this before)
'upcoming book this writer's' is the wordplay.
'upcoming' is a reversal indicator.
'book' becomes 'tome' (tome is a kind of book).
'this writer's' becomes 'ive' (belonging to me).
'tome' in reverse letter order is 'emot'.
'emot'+'ive'='EMOTIVE'
(Other definitions for emotive that I've seen before include "Causing strong feelings" , "Contentious" , "Stirring feeling" , "Affecting, moving" , "Move tie (anag)" .)