Confirmed communist returning food (9)

I believe the answer is:

provender

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'food' is the definition.
(I know that provender is a type of food)

'confirmed communist returning' is the wordplay.
'confirmed' becomes 'proven' (I can't justify this - if you can you should believe this answer much more).
'communist' becomes 'red' (red can informally mean communist).
'returning' says the letters should be written backwards.
'red' reversed gives 'der'.
'proven'+'der'='PROVENDER'

Can you help me to learn more?

(Other definitions for provender that I've seen before include "Animal fodder" , "Dry feed" , "Dry food for beasts" , "animal feed" .)

I've seen this clue in The Daily Express.

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