Kin Hubbard, the creator of the cartoon Abe Martin of Brown County, said, "Honesty pays, but it doesn't seem to pay enough to suit some people."
Playing suit combinations correctly pays at the bridge table. An expert enjoys an advantage because he knows so many of them, but even then, care might be needed. What should South have done in his four-spade contract after ruffing the third round of clubs?
Remember that you do not pre-empt against a pre-empt. Jump overcalls are strong. South has three top losers: two clubs and one spade. So he must find East with both of the red-suit kings. However, he probably needs to take three finesses: one in hearts and two in diamonds. This requires either lots of dummy entries or being able to run a card from the dummy that can win the trick assuming the finesse is successful.
Declarer has only one way into the dummy, via the spade eight. So he must carefully ruff the third club high, then lead a top trump. Let's suppose West wins and plays another club. South ruffs high once more and overtakes his spade two with dummy's eight. What next?
Suppose declarer runs the diamond nine. Then he will be stuck. If he leads the 10 next, he will have to win the trick with his jack, so he should try the queen, but East can cover with the king to strand South in his hand. Declarer should first lead the diamond queen and unblock his jack. Then he can run the diamond 10. When that holds, he plays a heart to his queen and claims.