Advocator of the amazing proton pen (9)

I believe the answer is:

proponent

'advocator' is the definition.
(I know that advocator can be written as proponent)

'amazing proton pen' is the wordplay.
'amazing' indicates an anagram.
'proton'+'pen'='protonpen'
'protonpen' with letters rearranged gives 'PROPONENT'.

'of the' is the link.

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

I've seen this clue in the Sydney Morning Herald.

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