Sorry, but unlike Roland's problems I am afraid this one is not 100% foolproof, and the best defence might just be a guess, still wanna see how you think these one:
From the bidding partner is around 11 HCP (9-11 after you see dummy) and you know it would be very hard that he passed at this vulnerability on third position with such a strenght and a 5♠ suit. That´s why you decide to lead ♥3 (dunno if you agree but have to stick to it).
♥3 goes to the 4, Q and 5.
Partner switches to ♠4, K, 8 and 3 (Std attitude).
Declarer plays ♦4, your 3, J and 7 (Std count).
Dummy plays ♣2, 4, J and your Q.
so far 1 trick on each suit has been played, and you are again on lead, what do you play?

Help

S - W - N - E
ps -ps -ps -1NT
ps -3NT-ps -ps
ps