Ok. Cherdano has it exactly right, imho, and for all the correct reasons. And, a few others, notable Flame and Trpltrbl (who guessed squeeze defense because it was me who posted the hand) as well.
Some of the comments during the hand was a
♦Ace and
♦ would not beat the contract, because East would be squeezed in the blacksuits, but West's
♠9 is a stopper because the spade threat has to be in South's hand (hence the
♠8 is the threat).
If south has the
♠9, then EAST "could" be exposed to a black suit squeeze, but of course, declearer might simply take the
♣ hook (if he had a club..hehehe) rather than play for the trifecta of EAST holding
♣K and either
♠QJ(x) or four
♠ to the Queen or JACK.
So the two options seem to be a trump back, and hope declearer with a singleton club and three spades, takes the
♣ hook. Or to exit a
♠ honor to break up a pending squeeze. The good news about a
♠ back, declarer will have to guess if you had
♠Qxx or
♠Qxx (as noted by Cherdano). As you can see from the actual hand, only a
♠ back breaks up the pending double squeeze. If the
♠ is won in dummy, there is no entry to the
♣/
♦ threat (after running trumps), and if the
♠ is won in south, there is no entry in the double threat suit hand.
Ben
West North East South
- - - 1♥
2♦ 3♦ Dbl RDbl
Pass 4♥ Pass 4♠
Pass 5♦ Pass 5♥
Pass Pass Pass