Support sole gutless nationalist supporter (9)

I believe the answer is:

proponent

'supporter' is the definition.
(thesaurus)

'support sole gutless nationalist' is the wordplay.
'support' becomes 'prop' (prop up can mean to support).
'sole' becomes 'one' (synonyms).
'gutless' means to remove the middle letters.
'nationalist' becomes 'nat' (short for nationalist).
'nat' with its middle removed is 'nt'.
'prop'+'one'+'nt'='PROPONENT'

(Another definition for proponent that I've seen is " Advocate (of a theory, etc)".)

I've seen this clue in The Telegraph.

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