Appear to swap parts for rally (6)

I believe the answer is:

upturn

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'for rally' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for upturn that I've seen before include "Rise" , "Improvement in business activity" , "Improvement in results" , "Improving trend" , "Rising trend" .)

I've seen this clue in The Independent.

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