6
♦ by N on a heart lead is interesting also if they lead another heart when in with the club (Overtake Q
♦ at trick 2, draw trumps and play a club).
Declarer ruffs a club and rumbles all the diamonds leaving:
and the 2
♦ executes the double squeeze.
It appears a spade switch when in with the club breaks this up.
K
♠ lead v 6
♦S:
A
♠ and ruff one,
♦ to Q and ruff another then rumble the trumps leaving:
Now you cross to a top heart and exit with the spade.
On a club lead, you have to switch to a spade, if you switch to a heart the double squeeze above works.
Pretty problem zenbiddist!
Simplified version