Dealer: South

Vuln: E/W

After the lead you can count 6 winners i.e. all the trumps and Heart Ace

Therefore you will need to generate 4 more winners. One will come from Diamonds and you will need to build three tricks in Clubs your second suit.

In situations like this its best to get your second suit established as soon as possible.

Should the clubs break badly, you might need to ruff 2 clubs in the dummy so if this is the case you will have to delay drawing trumps.

After winning the first trick, now enter hand with a top spade in order to lead up to the clubs in dummy. East takes his ace and plays a club back won by West. This play suggests that it is East who started with just 2 clubs. West takes his ace but doesn't play another club but instead  plays a trump to you. You can now win and draw the last trump ending in dummy. Now you can cash your winning clubs and claim 10 tricks by way of 5 trumps, 3 clubs 1 Heart and 1 Diamond.

Had West played back a third trump you would have to ruff with a high trump. to avoid being overtrumped and life would not be so easy. Then you would have to play up to your Diamond honours and hope East had the Ace which he does have.

(NB when declarer isn't drawing trumps, you, as a defender, need to attack trumps to stop declarer ruffing- here it works against the two defenders)