You are sitting North. You opened 1D in 3rd seat, East overcalled 1S, your partner raised to 2D, West cued 3D, and East signed off in 3S. The opening lead is is the Diamond 4 to the Queen King and Ace. Declarer plays the Heart Queen, won by your partner with the King. She cashes the Diamond Jack and leads a Heart to your Ace, East following. What should you do now?
You have 3 tricks in the bag and you have the Club Ace. You just need one more trick to set the contract. It seems as if your partner wants you to give her a heart ruff. Should you? Before you do, you should ask yourself, “Why is declarer playing hearts and exposing himself to a ruff? Why didn’t he draw trumps?” He can’t be worried about diamonds, as he can ruff his last one easily. The main reason for playing hearts is to establish the suit for discards. What could he be hoping to discard? Clubs. You can play the Club Ace and look for a signal from partner. If she encourages then play another club. If she discourages, try for the heart ruff. This gives you two chances to find the setting trick.
What actually happened at the table? Declarer ruffed the third heart high, with the King. He then pulled trumps and discarded 2 clubs on the hearts to make his contract. If you play the Club Ace your partner will signal with the 9. A second club sets the contract.