Potter a guaranteed success claims novelist (8)

I believe the answer is:

ceramist

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'potter' is the definition.
(synonyms)

'a guaranteed success claims novelist' is the wordplay.
'a guaranteed success' becomes 'cert' (I can't justify this - if you can you should give a lot more credence to this answer).
'claims' means one lot of letters goes inside another.
'novelist' becomes 'amis' (Kingsley or Martin Amis).
'cert' enclosing 'amis' is 'CERAMIST'.

Can you help me to learn more?

(Another definition for ceramist that I've seen is " Potter".)

I've seen this clue in The Independent.

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