I thought the singleton diamond was a reasonable lead. It went to partner's king, and partner led one back for me to ruff. I didn't like the look of the ♦A or the heart suit potentially providing discards, so cashed my ♣A and switched to a heart. Declarer went up with the ace, drew trumps in two rounds ending in dummy, and threw the heart loser on the ♦A. 10 tricks made.
The problem was I am ruffing with a natural trump trick (I didn't know this at the time), and at the same time setting up dummy's ace for a discard, hence I gave a trick away. I need to lead a heart at trick one to establish partner's king, and not setting up a diamond discard for declarer. This holds it to nine tricks.
Here's me thinking the standard opening lead advice was to lead partner's suit he has overcalled.