Use extreme caution in secret redesign of French pastry shape (8)

I believe the answer is:

crescent

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'shape' is the definition.
(crescent is a kind of shape)

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

(Other definitions for crescent that I've seen before include "Waxing process could show one" , "Curved street or terrace" , "Curved row of houses" , "looking sickly" , "Moon shape; curved street" .)

I've seen this clue in The Irish Times.

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