Bidding:
Pard South you North
pass . 1♠ ... 2♥ . 4♠
. 5♥ .. 5♠ (all pass)
You lead the A♦ and see
Pard plays the 7 (attitude, low = enc), while declarer follows with the 10. You wiggle for a while and decide to cash the ♦K. Pard plays the 6 and declarer the 9. What now?

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South plays 5♠