The diamond lead will knock out your ace and expose two losers in that suit. Because you must also lose the ♥A, you can’t afford to lose any more tricks. What do you plan to do about your third-round club loser?
You might say, “Easy. I’ll draw trumps and play on hearts, I can eventually discard my losing club on a high heart.” But this plan is flawed. If you draw trumps in three rounds (or four if necessary) and then play a heart, the defense will surely duck the ♥A on the first round of the suit. When the defense wins the next round of hearts, you’ll be cut off from dummy, with no way to get to your established heart winner.
So the trick on this deal is to not draw all the enemy trumps yet. After winning the ♦A, cash the ♠A and play a low heart to dummy. If the defender with the ♥A ducks, play a trump to your queen and play another heart. The defense will win and cash their diamond winners, but the ♠K is still in dummy, a vital entry to the good heart.
