Quite a few Souths got the play of 6♥ wrong on this hand. The Ace and King of Spades were led, declarer ruffing the second one, and he played out the Ace of Hearts, discovering the bad news. Those who went over to the King of Diamonds, finessed in trumps, then drew them all, relying on the clubs to break 3-3 went two down. The correct line is, after drawing just one round of trumps, to play the Queen/Jack of Clubs, then play the Ace of Diamonds and go over to dummy with the King of Diamonds and now play on clubs. East can ruff, but South can now over-ruff, draw the rest of the trumps and there will still be a trump in dummy to reach the rest of the clubs.