We need to end up in dummy with all the trumps drawn and the diamonds unblocked. There are two ways to unblock: playing the suit, and discarding the blocking cards. We can't play the suit before drawing trumps because West is void, and we can't discard ♦AK before trumps either because we have only one master in dummy to discard on. We can't play the suit after drawing trumps because we will be stranded in hand, and we can't discard after drawing trumps, again because we have only one master in dummy.
That leaves us with only one possibility. We have to discard while drawing trumps. We need to discard one of our blocking diamonds on one of dummy's trumps and the other blocker on ♠A. So we have to shorten our trumps by two. This can only be done by ruffing spades, so we must discard a diamond at trick one.
Play the ♦7 from dummy and take the first trick with our ace. Play a first round of trumps and then ruff ♠7. Play a second round of trumps and then ruff ♠Q. Play a third round of trumps with our last trump from hand. Now draw West's last trump and discard ♦K. Cash ♠A and discard ♦A. Dummy's diamonds make the remaining five tricks.
