Former Prime Minister’s zest (4)

I believe the answer is:

peel

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

I don't understand how the rest of the clue works.

(Other definitions for peel that I've seen before include "Outer fruit layer" , "5,27 [PRIME MINISTER]" , "zest, getting out of this scrape?" , "A PM; a fortified tower" , "Take skin off fruit" .)

I've seen this clue in The Times.

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