S/NS		♠	10 6 5
		♥	K J 10 2
		♦	A K Q 7
		♣	5 4
				♠	—
				♥	A Q 8 6 4
				♦	10 9 8 3
				♣	A 9 3 2

¹ Slam try: establishing spades, showing a diamond control, denying a club control
² Heart control and therefore a club control as well (without a club control South would have bid 5♠!)
³ 'I've done enough'

West leads the ♣Q. East wins with the ♣A, South following suit with the ♣8.
How should East defend?

W/NS		♠	A 10 9
		♥	Q 10
		♦	Q 4 2
		♣	K Q J 9 3
♠	8 7 6 4
♥	7 6 5 3
♦	K J 9 5
♣	A

West leads the ♠7, via North's ♠9 and East's ♠2 (discouraging) to South's ♠K.
Declarer continues with the ♣4 to West's ♣A, North the ♣3, East the ♣2.
How should West defend?

Defending is more difficult than declaring. Partly because defenders see only half of their party's cards. That disadvantage is far from compensated by the fact that they can see dummy's cards.
The declarer can see all of his 26 cards and can decide the strategy all by himself. Defenders have to agree on which strategy to follow, though they cannot see each others hands.
Usually declarer can easily perceive the defenders' strategy. On top of that he can benefit from their signalling.
For the defenders it's often difficult to grasp the declarer's strategy. Still that is an important part of defending. Therefore a defender should try to 'think along' with declarer. If he understands the latter's problems and possibilities, he can defend better. That is why a good defender prepares for what may happen whenever declarer is thinking.
In this problem it is absolutely essential that West does so.

E/EW		♠	A Q
		♥	10 9 4
		♦	A Q J 10 3
		♣	A Q 2
♠	10 7 2
♥	Q 8 7 5 3
♦	9 4
♣	K 10 9

West leads the ♥5 (fourth best). East wins with the ♥A, dropping South's ♥J. East returns the ♥6, South winning with the ♥K.
While South is planning his play (too late, he should have done so before playing to the first trick in dummy!), West thinks along and anticipates the likely continuation. How?