Jack’s cards (6)

I believe the answer is:

knaves

I believe this is a double definition.

'jack's' is the first definition.
(I know this)

'cards' is the second definition.
(knave is a kind of card)

(Other definitions for knaves that I've seen before include "Four face cards bearing a picture of a young prince" , "Loons" , "Jacks (cards)" , "Scoundrels" .)

I've seen this clue in The Mirror.

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