The supporter is there and changed (8)
I believe the answer is:
adherent
'the supporter' is the definition.
(thesaurus)
'there and changed' is the wordplay.
'changed' is an anagram indicator.
'there'+'and'='thereand'
'thereand' anagrammed gives 'ADHERENT'.
'is' is the link.
(Other definitions for adherent that I've seen before include "Freak" , "Weep" , "Supporter; sticking" , "Supporter, follower" , "supporter of party" .)