Source: ACBL Chicago Bulletins
Opening lead: 
A
Bidding Commentary: South’s jump to 3 is invitational and North’s delayed support at the three level is forcing. 4
by South is automatic.
Lead Commentary: As West, the bidding has tipped you off that North-South have at least eight clubs between them, more likely nine. Since partner has a singleton or void in clubs why not double? The only reason for not doubling is that you might chase them to 5, but that is unlikely.
Defensive Commentary: Not much to the defense after the lead. You continue with the 9, suit preference for spades, East ruffs, returns a spade to your ace and ruffs the club return for down one. Nice double and nice defense using the bidding to guide you.