Trump Too Can Offer an Entry

Even When there are None Outstanding

9 7 5
A J 8 7
K J 9 6
5 4
Q J 10 6 4 A 3
6 2 10 4
5 4 2 A 8 7 3
K 10 3 Q J 9 8 6
K 8 2
K Q 9 5 3
Q 10 Contract: 4 hearts
A 7 2 Opening lead: Q of spades

It's an anomaly in bridge that while some careless declarers cash one round of trump too many, when dummy's trump should be used to ruff a card from the closed hand, others of a contrary stripe can't think of using trump as an entry, though they have no other entry, and the trump isn't already slotted to ruff a card from the closed hand. I recently came across two such situations, the second one to be given here
West led the Q of spades, East going up with his Ace, shooting a spade back, declarer winning. Now came two rounds of trump, then a diamond to the Q, holding followed by the 10, which East took, immediately shifting to a club. Let's stop and take stock:
We have lost two tricks -- the A of spades and A of diamonds -- and stand to lose a club as well as a spade unless we can get to dummy to cash out the established diamonds. Unfortunately, this declarer didn't see how, it would seem, and chose to cough up a club to the defense, and West winning, naturally cashed out a spade trick.
Declarer can, of course, ruff the third round of clubs in dummy, but that's locking the barn door after the horse is stolen. He doesn't need that ruff, and indeed, since he can't get it without coughing up the setting trick, he should be looking for a way to utilize his lovely diamonds in dummy. And he shouldn't have found it difficult to spot. For he has an entry in hearts, whereupon he can cash two diamond winners, sluffing either two clubs, conceding a spade, or a spade and club, conceding a club. Bid and made.