Person with an interest in interest? (5)

I believe the answer is:

saver

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'person' is the definition.
(saver is a kind of person)

I can't explain the rest of the clue.

(Other definitions for saver that I've seen before include "One putting money by" , "Careful user of a piggy bank?" , "One budgeting" , "Cheap fare" , "one in recovery" .)

I've seen this clue in The Sun.

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