Just the sort of sum to clear up (4)

I believe the answer is:

tidy

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'clear up' is the definition.
(I've seen this before)

I can't explain the rest of the clue.

(Other definitions for tidy that I've seen before include "Neat and orderly" , "small container in which odds and ends are kept" , "Spick-and-span" , "Large" , "Considerable (sum); neat" .)

I've seen this clue in the Evening Standard.

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