The north hand may seem a bit heavy for 1NT, but the choice paid off when East led a ♥. Now declarer can guess wrong in ♣ and still make a critical overtrick. But a funny thing happened along the way:
When West played the ♥J, declarer won with the Ace! Now after drawing trump, he led the ♣K and ran the Ten. In with the Queen, East led the ♥7.

Help

1NT-P-2♣-P-2♠-P-3♠-P-4♠-P-P-P