Rule out chapter in introduction (8)
I believe the answer is:
preclude
'rule out' is the definition.
('preclude' can be a synonym of 'rule out')
'chapter in introduction' is the wordplay.
'chapter' becomes 'c'.
'in' is an insertion indicator.
'introduction' becomes 'prelude' (I've seen this before).
'c' put into 'prelude' is 'PRECLUDE'.
(Other definitions for preclude that I've seen before include "Debar" , "Prevent, forestall the possibility of" , "Prevent (something) from happening" , "'Prevent, forestall (8)'" , "Obviate, prevent" .)