This hand intrigued me. It came up in the semifinals of the Bulgarian Team trials.
You hold:
2♣ showed 10-15 with either 4M and 5+C or 6+C. 4♥ was an amorphous game force.
After due consideration you decide to lead your singleton (would you?).
You see the following:
Declarer pauses, then wins the ♦A on which partner plays the UDCA 5 and declarer the 2. Declarer continues with the ♣7 to the 4, Q and your 3. The ♣K is led, you win the A, dummy pitches a ♦, and partner follows with the 9. Partner's club play is consistent with a doubleton.
Your play.
Benefits include:
Plus... it's free!