Nail caught on decree (4)

I believe the answer is:

claw

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

I cannot understand how the remainder of the clue works.

(Other definitions for claw that I've seen before include "See 24" , "Lobster's grasping structure" , "Hook on the end of toe" , "Bird's foot" , "Hooked nail" .)

I've seen this clue in The Mirror.

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