How should South play in four hearts after West leads a low spade, given that the trumps are not 4-0?
In the auction, South might have opened one heart, but if North had responded one spade, South would have had to rebid two clubs, which would not have been ideal. So, one-no-trump was sensible. Then, North should have raised to three no-trump. Do not use Stayman with 4-3-3-3 distribution, especially with such a weak major. Note that South would have had nine top tricks.
In four hearts, declarer has three diamond losers, so he seems to need to find the club queen. That is how every robot played, most going down, but a couple succeeding because West discarded clubs while declarer was drawing trumps.
The contract is 100 percent. After winning trick one and drawing trumps, declarer cashes dummy’s second high spade, ruffs the last spade and exits with a diamond.
The defenders take their three diamond tricks, but are trapped.
If a club is led, it finds the queen for South; if a spade or diamond is returned, declarer receives a ruff-and-sluff. It is a textbook elimination and endplay.