You start with nine top tricks: five spades, the ♥A K and the minor-suit aces. You can get a 10th trick from ruffing a club in dummy, but you know from the bidding and the play that West is void in clubs. (East preempted at the three level, so he’s very likely to have seven clubs. West’s failure to lead his partner’s suit is further confirmation that the suit is 7–0.) The full deal:
So how can you ruff a club in dummy without allowing West to ruff your ♣A? Win the opening lead and play a low club from your hand at trick two. West will likely discard something, and East will win the trick. Whatever the defense does next, you will play another low club toward dummy, overruffing with the trump ace if West ruffs first. Then you will draw trumps and claim, scoring five trumps in your hand, one club ruff in dummy with the ace, and four top tricks in the side suits.
