South dealer, All Vul.
Lead: Ace of hearts, followed by the king (the ten and the three from East), then the queen, which you ruff when East discards the diamond two.
Do you see a way to get an additional trick thanks to a ruff?
Yes, when you ruff the third diamond with a trump in the North hand, the short side.
Which supplementary chance of getting a trick to you have?
The finesse against the club queen with East. Unfortunately, if it fails, you must not lose a trick to the trump queen: