Intellectual argument in support of very important bishop (8)
I believe the answer is:
highbrow
'intellectual' is the definition.
(highbrow is a kind of intellectual)
'argument in support of very important bishop' is the wordplay.
'argument' becomes 'row' (I've seen this before).
'in support of' is a charade indicator (letters next to each other) (I've seen this in other clues).
'very important' becomes 'high' (I am not sure about this - if you are sure you should believe this answer much more).
'bishop' becomes 'b' (abbreviation used in chess).
'high'+'b'='highb'
'row' put after 'highb' is 'HIGHBROW'.
Can you help me to learn more?
(Other definitions for highbrow that I've seen before include "Highly cultured or educated" , "Intellectual - cultured" , "Person of erudite tastes" , "Intellectual with lofty forehead?" .)