This is an easy one, provided you don’t rush. After winning the trump lead in hand, unblock the ♦A, cross to dummy with the ♣K and discard the ♠Q on the ♦K. All that is now required is to manage clubs for one loser.
If your second play in clubs is leading to the ace, the result in the layout shown will be a debacle. West ruffs the ♣A and returns a trump, leaving you with two club losers and only one trump to cover them. So slam will fail.
The safety play is to duck the second round of clubs! After that, the defenders are without recourse. Even if West ruffs his partner’s club winner so that he can play another trump, you will still have a trump left in dummy to ruff your remaining club loser.
When I showed this hand to the leading British writer, David Bird, he observed that the trump opening lead was a good choice. “Many players would have led the singleton club, but there is little point in this. West has seven points himself and can hardly expect his partner to hold an ace when the opponents are in a slam.”
After an initial club lead you survive even if the ♣A is ruffed and a trump is returned to your ace, because there are still two trumps in dummy to deal with both of your remaining clubs.
