Intellectually deep academic certain to release book (8)
I believe the answer is:
profound
'intellectually deep' is the definition.
(I've seen this before)
'academic certain to release book' is the wordplay.
'academic' becomes 'prof'.
'certain' becomes 'bound' (as in the phrase 'it's bound to be').
'to release' is a deletion indicator.
'book' becomes 'b'.
'bound' with 'b' removed is 'ound'.
'prof'+'ound'='PROFOUND'
(Other definitions for profound that I've seen before include "deeply intellectual" , "showing great knowledge" , "Far-reaching" , "Overpowering" , "Extensive" .)