Answer
You (4th seat, none vulnerable) are declaring.
The opening lead is the Ace of diamonds (three, ten, seven); West continues with the King of diamonds (four, nine, and you ruff). What’s your plan? NS have only 21 combined HCP, so probably most auctions will stop below game. So, just making this contract should provide a good matchpoint score. Fortunately, making the contract will be easy if there is no club loser; all you need is for trumps to be 3-2 and to score a heart ruff in the dummy. Looking at the spade suit in isolation, it seems attractive to take two finesses, but that approach isn’t a good one, when you consider the full deal. For one thing, after you ruff a heart in dummy, you can’t finesse twice in trumps. For another, now that West (who passed as dealer) has shown up with the Ace-King of diamonds, West cannot have the King and Queen of spades.
So, after ruffing at trick two, here are two good lines of play: (1) Spade to the Ace, heart to the Ace, ten of hearts ruffed, ten of spades; and (2) Spade to the ten (probably losing), then when you regain the lead, take a heart ruff in dummy and lay down the Ace of spades, hoping that the remaining honor falls. Line (2) is better, giving you a chance for eleven tricks.
The full deal appears on the next page.