Opening Lead: ♥10
Had South made a take-out double instead of overcalling, as most would have done, North would have had to decide what suit to bid and at what level. After the overcall, North only had to decide how many clubs to bid. North chose to bid a slam in clubs and it was up to South to make it.
Declarer won the opening heart lead with his ace, led a club to dummy’s jack, and cashed the ♣A. This drew the trumps, so South led a diamond from dummy to his king as East ducked his ace. The ♦J lost to the ace and East continued with another diamond. South cashed dummy’s two diamonds, discarding a spade, and took a moment to plan the rest of the play.
South had kept his eyes wide open. He knew that East had started with six hearts from the auction, and East had followed to four diamonds and two clubs. East therefore had a singleton spade. Should that singleton be the queen, cashing dummy’s ace would bring it down and give declarer 12 tricks. The slam could also be made against the singleton 10 or nine in the East hand. This was twice as likely as the singleton queen, so South crossed to his hand with a trump and led the ♠J. This was covered by the queen and dummy’s ace, and the fall of East’s nine was a pleasant sight.
South again crossed back to his hand with a club and led a spade to dummy’s eight with great confidence. Well played!