Egghead needs support on popular TV (8)
I believe the answer is:
brainbox
'egghead' is the definition.
(I've seen this before)
'support on popular tv' is the wordplay.
'support' becomes 'bra' (a support for the breasts).
'on' means one lot of letters go next to another.
'popular' becomes 'in' ('in' can mean trendy).
'tv' becomes 'box'.
'bra'+'in'+'box'='BRAINBOX'
'needs' is the link.
(Other definitions for brainbox that I've seen before include "Mastermind" , "one's very bright" , "Clever type" , "Egghead" , "Einstein?" .)