The bar is starting point. All you need is lockpick and lethal poison. Note that Revolutionary's location is random, so you may need to restart a few times.

1. Get an outfit of guard. He's not so far from the bar and close to trash bin.
2. Lockpick doors of house near the water.
3. Wait until Revolutionary leaves the house with guards (one will stay inside).
4. Enter the house (avoid the camera) and poison his wine.
5. Leave the house and wait for a bus.