Turkey supporter follows game at home (9)
I believe the answer is:
lamebrain
'turkey' is the definition.
(I've seen this before)
'supporter follows game at home' is the wordplay.
'supporter' becomes 'bra' (a bra gives support to breasts).
'follows' is a charade indicator (letters next to each other).
'game' becomes 'lame' (I've seen this before).
'at home' becomes 'in' (similar in meaning).
'bra' put after 'lame' is 'lamebra'.
'lamebra'+'in'='LAMEBRAIN'
(Other definitions for lamebrain that I've seen before include "turkey" , "Idiot" , "Nelly" , "two [TOMFOOL] ..." , "fool" .)