Intellectual brother in Rye? (8)
I believe the answer is:
cerebral
'intellectual' is the definition.
(I know that intellectual can be written as cerebral)
'brother in rye?' is the wordplay.
'brother' becomes 'br' (abbreviation in titles of monks).
'in' indicates putting letters inside.
'rye?' becomes 'cereal' (rye is a kind of cereal).
'br' going into 'cereal' is 'CEREBRAL'.
(Other definitions for cerebral that I've seen before include "Concerning the brain" , "Intellectual, brainy" , "Of the brain, intellectual" , "Relating to the brain" , "Highly intellectual" .)