2Dark

Ok so you will get the opportunity to get this achievement mid way through the first level (it is missable).

After working your way through the ghost train, you will come to a section where the clown is making 3 children in costumes jump through hoops.

You are locked behind some gates, so can't get to them. What you want to do is select your candy with Y and then if you look ahead there are 2 levels in front of you just past the gate that you can't get through. Make sure the right one is highlighted red, and pull RT to throw Candy at it. This will open the gate in front of you.

Now enter the room and get the clown to come after you and head back to where you started. What you want to do is get the clown in the cage section where you started and then nip past him and shut the gate (using the same lever) so he is trapped in (and you are not).

Then you can trigger the left hand lever, which will open the lion cages. They will maul him to death, and as such, achievement unlocked!! Good luck!!