Intellectual greeting on the radio, before b_____ argument (8)
I believe the answer is:
highbrow
'intellectual' is the definition.
('highbrow' can be similar in meaning to 'intellectual')
'greeting on the radio before b argument' is the wordplay.
'greeting' becomes 'hi' (hi is a kind of greeting).
'on the radio' shows a homophone (sound like).
'before' means one lot of letters go next to another.
'argument' becomes 'row' (I've seen this before).
'hi' sounds like 'high'.
'high'+'b'+'row'='HIGHBROW'
(Other definitions for highbrow that I've seen before include "Intellectual with lofty forehead?" , "Highly cultured or educated" , "Intellectual - cultured" , "Person of erudite tastes" .)