South opened 1♠ and after North had shown at least a raise to 3♠ with the 2NT bid, a series of cue bids (slam tries) followed. The first of these (3♣) showed a singleton or void in Clubs. The others were all either showing the Ace, the King, or a singleton or a void in the suit bid.
Note how North/South made FOUR slam tries on their 21 HCP before eventually stopping in 4♠.
West leads the 5 of Spades. You have been given a chance to make 12 tricks. Make your plan before clicking on Show All Hands and finally clicking on Answer.
Opponents have drawn trumps nicely for you. You could lead towards the K♣ hoping the Ace is on your left but of course, it never is. Sometimes, you get a "feeling" that things are wrong and you decide to play for the tiny chance that East has the Ace of clubs (and most importantly, just two other clubs).
Play a small club towards the King and when West plays the 2♣, play the 8♣. If West plays the 10♣, play small. When you lead small from a "known, advertised singleton/shortage", most players usually play the Ace if the have it in front of the King. Hence, If West plays small, you are probably wasting your time playing the King because it will lose to the Ace with East. If East wins unexpectedly with the 9♣, win any return, go to dummy and trump the second Club. Return to dummy and lead a third small Club. If West wins with the 10♣ just play the same. Do not play the K♣ at any time. Begin to feel sorry for East when the Ace of Clubs is played per-force on the third round.
Your 12 tricks have materialised and you have a place to park your losing Diamond.
If West had led a Club, you could still have played the same. Just do not play the King of Clubs on the Q !!! A diamond lead would always hold you to 11 tricks.
Of course, the Ace could have been correct all the time, everyone would have made 12 tricks and you could have looked foolish. 5 Tables in play - 4 others make 11 tricks and you have your "top".
To quote Hannibal Smith from the T.V. series (and now movie film) 'The A-Team', "I love it when a plan comes together..."