Based on several factors, including the tempo of the auction and partner's known conservative streak, you double the final contract.
Expecting declarer to have spade shortage, and not seeing any obvious source of discards for a possible singleton spade (while holding trump control), you lead the ♥9.
Declarer wins the ♥King, cashes the ♥Queen, cashes the ♣Ace, and ruffs a club in the dummy. Now comes the ♥Ace, declarer pitching the deuce of spades.
Plan the defence.