meaning

[daisy1352]

Now, facing bankruptcy and a possible jail sentence, George decides to end his life by jumping into the river. Enter Clarence, an angel sent to help him. Clarence jumps into the water first, certain that, as always, George would put aside his own problems....
What is the meaning of "enter Clarence"? If it has the meaning of "enter" why don't we say "Clarence enters"?
Thanks a lot

[bhaisahab]

Now, facing bankruptcy and a possible jail sentence, George decides to end his life by jumping into the river. Enter Clarence, an angel sent to help him. Clarence jumps into the water first, certain that, as always, George would put aside his own problems....
What is the meaning of "enter Clarence"? If it has the meaning of "enter" why don't we say "Clarence enters"?
Thanks a lot

It's like a stage direction.