Song patriot rendered as supporter (11)
I believe the answer is:
protagonist
'supporter' is the definition.
('protagonist' can be a synonym of 'supporter')
'song patriot rendered' is the wordplay.
'rendered' indicates anagramming the letters.
'song'+'patriot'='songpatriot'
'songpatriot' anagrammed gives 'PROTAGONIST'.
'as' is the link.
(Other definitions for protagonist that I've seen before include "Hero" , "Leading player" , "Chief character in a story" , "Key character in a novel" , "Advocate" .)