A safeguard against pirates: that’s clear (6)

I believe the answer is:

patent

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

I cannot understand how the rest of the clue works.

(Other definitions for patent that I've seen before include "Obvious - property right to invention" , "Registration of an invention or trade name" , "The invention protection is obvious" , "For all to see" , "Manifest" .)

I've seen this clue in the Evening Standard.

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