If you've got to the room with the clown face, then you haven't gone far enough. The only clown face I remember is on a map where it is roughly in the middle of the map, towards the left.
It is where you get the key.
You leave that map via a long staircase at the bottom left corner. That takes you to a map where you cross the roof with sky behind you, and then down a long staircase (same map as the clown room)
You have a fight at the bottom.
Carry on from there.