Yes, a Nine-high Suit

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

West opened the play the ace of hearts. His partner did his best, signalling with the 5, the highest card he could spare, but West shifted to the jack of spades. Declarer still shouldn't make it. Indeed, as played, he should go down two! How did that thing (the computer) make slam? I wondered when it proved to have done so. It wasn't West's failure to continue hearts that did it, well, not that alone. It was a careless discard from a four-card suit that allowed declarer to sail home with his contract.
West shifted to the J of spades, which was won in the closed hand, and declarer now led a diamond to the ace, ruffed a diamond, then led to the Q of spades and back to the K, West sluffing a club on the third round. Declarer now ran five clubs, sluffing a heart and three diamonds, ruffed a heart and cashed the king of diamonds, sluffing the closed hand's last heart. Winners were five clubs, five spades and two diamonds.
I just can't emphasize the importance of saving your four-card suits as long as you can (by and large -- I don't advocate throwing away aces and guarded kings to save a 9-high suit. Rather, I'm saying that discarding from a 4-card suit should be done with great reluctance). Oh, but West has two four-card suits here (in my lexicon "four-card suit" includes anything longer). Yes, true, but that is a five-card suit and the bidding makes it virtually impossible that declarer has five of them, when he bid a four-card spade suit without mentioning hearts (and you'd have wanted to give your partner a ruff if declarer did have 5 hearts), so that should clearly have been West's first discard, getting down to four cards. That gives him at least one trick to think, and beyond thinking, the hand may be clarified by the time the real crunch comes, as it would have been here. For the hand would then have looked like this:

6
6
K 10 7 5
3
------ ------
10 9 8 K 3
------ Q J
9 8 6 2 J 10 7
------
Q J
------
A K Q 5 4

Look at declarer's choices at that point. He can run three clubs, sluffing a heart and diamond from dummy and ruff a heart. But now he's locked in dummy and East will control the last two tricks with a diamond and that K of hearts. Or he can run three clubs and ruff a club, "establishling" the fifth club, if that's the right word when he has no access to it. (That's how he could have played the hand one trick better, by establishing the 5th club while retaining a fourth spade for re-entry.) With a lotta high trump in dummy, he could have ruffed diamonds twice in the closed hand, using trump for re-entries, ending in dummy, then run two diamonds, followed by two top clubs, sluffing dummy's remaining heart (the third round of clubs becomes redundant in that case). But he didn't have a lotta high trump and you can see that he cannot afford a third round of diamonds until all trump are out and so cannot establish the suit.
So West would have had no problem if he'd just discarded a heart from that five-card holding rather than a club from the four-card. Declarer can't even pseudo-squeeze him, can't even give him a difficult choice to make. Declarer's looking at a hand where he has only clubs and hearts himself. Guess which suit he's going to lead. Actually, West doesn't need to guess. He'll beat the contract or allow his partner to do so if he just follows suit.
So he's not squeezed and not pseudo-squeezed. He just needs to discard from a five-card holding in a suit that's surely not going into the 5th round, and the hand will unfold without further problem. When declarer leads his clubs, West follows and will control the fourth round of the suit -- control, not win. But if by so doing, he forces declarer to be locked in dummy, allowing East to win the last two tricks, or if on another line, declarer ruffs out the fourth round of clubs and thus cannot ruff his last heart (throwing one on the second diamond honor), West will be instrumental in defeating the contract as much as if he'd continued hearts at trick 2.
A powerful card that 9 of clubs, eh? Of course it might have been wiped out on four leads if declarer had the jack or 10. But you don't know it can be wiped out and when you have an easy discard in the 5th card in another suit, you'd do well to hang onto the four-card holding until you have a real problem. And that is the point of this category, that four-card holdings so commonly become important that one would be wise to discard useless cards until there is a real problem. No real problem would have surfaced here. West wouldn't even have had to choose between discarding from four hearts or four clubs.