Protection from propriétaires (6,7)

I believe the answer is:

french letters

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'protection' is the definition.
(I've seen this before)

'from proprietaires' is the wordplay.
I cannot quite see how this works, but
'from' could be 'fr' (abbreviation) and 'fr' is found within the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?

(Other definitions for french letters that I've seen before include "protection" , "Those sent after 16 [AGINCOURT] would have been miserable" .)

I've seen this clue in The Sunday Times and The Times.

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