Two declarers made six spades here. Making six? A glance at the cards would indicate two club losers, since diamonds don't split favorably and you're not going to get rid of a loser on a heart, are you? An examination of the first declarer's play quickly dispelled any mystery about how the hand was made.
Declarer took the opening lead, led a club to the 10 and ace, West playing the 9, then a spade to the ace, ruffed a heart, a spade to the king, ruff another heart, run three diamonds, ruffing the fourth, and then a club. West had only a heart and diamond left and had to give declarer a sluff and ruff, allowing declarer to make.
Declarer's play is to be commended. If you want to catch a careless defender with a bare king for a throw-in, it's a very good idea to lead the suit early before the defenders get their heads screwed on right. The club from dummy was led at trick two, indicating that declarer saw his opportunity from the beginning and was lucky enough to catch both a napping defender and a K doubleton of clubs together. How about West? Does he deserve censure? Oh, I wouldn't go that far. It's kinda tough to toss a king under an ace so early as trick two. You could argue that West should ask, Why didn't declarer finesse if he's got the queen? and thereby know to unblock. But that's a lot easier to see in the post-mortem with unlimited time than at the table. I like to stick to the obvious, for there are plenty of errors right there, and so I'm not going to stick it to West. Still, it is worth some consideration, that if declarer leads a suit with only small cards in dummy and plays the ace, he would seem to be without finessing potential. But don't quote me as saying that will invariabaly be so!
The other declarer made the hand in a more roundabout and bizarre manner. He handled the club suit quite differently, ducking the first round and winning the second, after having drawn trump. Now he has to lose a second club, doesn't he? He can't get a sluff-and-ruff since that would mean giving up the lead to the defense. No, but he got a 12th winner in this manner:
After winning the second round of clubs, he took three rounds of diamonds, ruffed a fourth, led a spade to the jack, and ran the suit through trick 11 as the opponents each got down to one heart. West's other card was a diamond while East's was a club guard, a very necessary card to keep. So declarer went to the ace of hearts, dropping the king and queen, and took the last trick with the 4.
Was it clever double squeeze? No, it wasn't a double squeeze. Declarer has no more diamonds! And West should certainly have known it, having been the guardian of round 4. So to blank a king from a K J holding in order to save a diamond in a suit that can't be led is foolish in the extreme. East had to save that club and thus blank his Q. But West has no excuse.