Diamonds are possible, but west has no entry. East can set up one long spade, but that's only one trick. With west on opening lead, he obviously cannot attack hearts. So instead he heads a diamond to east's king, and east shifts to a heart. The king of spades is led off dummy, and east ducks two rounds then wins the third, and exits a heart.
South plays low, west plays low, and the ace in dummy wins.
Declarer now attacks clubs. Q East is in, and can exit a heart, but then the suit has blocked. South's entries seem tied up, but actually, declarer can win two clubs, pitch a spade, and set up his 8th trick in diamonds. Indeed they do. They can make 8 tricks in clubs.