Say you draw trumps and find them 3–2, West discarding the ♣3 on the third heart. Plan the play from here.
Start by crossing to the ♦A, giving up on 5–0 diamonds with West (you’ll see why soon), and assuming both follow, return to the ♦K. If diamonds are 3–2 or if East had a singleton 10 or jack (in which case you can pick up the suit by finessing the 9), strip diamonds and lead the ♣A and a club, falling back on the spade finesse if East has the ♣K (unless it is doubleton, in which case East must exit a spade).
If diamonds are 4–1, and either player started with J–10–x–x, you are back in your hand with the ♦K (why you crossed to the ace originally) to take the spade finesse. Assuming it wins, cash the ace, ruff a spade, cash a third diamond and exit a diamond, hoping the player who wins has to lead from the ♣K.
Also, if diamonds were 5–0 with East having the void, he might have doubled 6♥ for the lead.
Opening lead: ♣J
You win the king and lead a diamond to the jack, which holds. You continue with the ♦A, discarding a heart, and West plays the 10. Knowing West is not capable of falsecarding with 10– x–x, you lead a spade to the jack and king. Back comes a club to your ace. Now you are on your own. Plan the play from here.
You have to play for a trump coup, which means getting to dummy three times, twice to shorten yourself and once to lead from there to execute the coup.
Cross to a spade, and assuming both follow, ruff a spade. Next take the heart finesse, which wins (something has to work!) and ruff another spade, coming down to a heart, the ♦K 9 and a winning club.
Dummy has a fifth spade, the ♥A J and a club. Cross to the ♥A, (you don’t need the finesse) and lead that last spade.
If East ruffs, overruff, draw the last trump and take your 12th trick, a high club. If East discards, discard your high club and take the last two tricks with the ♦K 9.
Two defensive points: (1) If West started with 10–x–x in trumps, he should drop the 10 on the second round. Now when declarer goes to shorten himself by ruffing spades, West might be able to overruff and give partner a club ruff. Two defensive trump tricks when none were coming!
(2) East should return a heart upon winning the ♠K, killing a dummy entry prematurely, thus ruining the timing for your trump coup.
Thanks to Danny Kleinman, Los Angeles CA, for this one.