I, Cliff as declarer, was asleep on this deal.

The bidding was
S    W    N    E 
1H   P   1S   P
2C   P   2H   all pass  

West has a difficult lead. If West leads the SA, then Declarer will surely make 9 tricks. A club lead looks wrong, and I would probably choose a trump. But West chose the best lead, the D2. The defence played 3 rounds of diamonds.

Declarer can see 8 tricks (5 trumps and 3 clubs) and 4 certain losers. So the whole play is about winning the 9th trick. (If clubs are 3-3 there is no problem, so Declarer thinks about how to handle a 4-2 distribution, with one defender holding CJxxx or C10xxx)

The obvious play for Declarer at trick 3 is to discard a spade, and leave the problem of what to do next to East. (The expectation would be for East to lead a spade, but East can tell that this will be a disaster, because Declarer will be able to ruff out the second top spade.)  East may well select a trump, but Declarer will have no problem in dropping the A & K of spades in normal play, while still having an entry to the SQ.

The CJ would be more of a problem, but Declarer would still establish the SQ.

Missing this obvious play, I ruffed high, drew trumps in 3 rounds and led a spade. West won the SA and returned the DK. Again, I missed the obvious play of discarding a spade. West would have to continue with a club, which would be won in Dummy. A spade ruffed with Declarer's last trump would drop the SK, but even if that did not happen, either hand holding 4 clubs and the SK would have been squeezed.