"Ray" writes:

R We had a very beautiful, healthy coral bark maple tree which was about
eight years old, and 10 feet high.

It was destroyed when a nearby tree fell onto it, leaving only a tall
stem, with one sprig of leaves about a foot long sticking out of the
side.

Question: What if anything can I do to restore this tree?

You can see a photo at:

https://sites.google.com/site/10test20/

I had a Locust damaged worse than that by deer.
Who knew they'd try to eat a 4 foot tall tree in it's entirety.
What they didn't eat, completely, they stripped the bark from.
What was left looked similar to what you've got.

Back in the cage it went and it's recovered to it's 4 foot size
this year.

I think your tree has a chance.

--
Dan Espen