Repotter

It appears to be the top of the tree. So I would want to bring a side branch up to use for a new apex.
To do this you would have to trim some of the area of the trunk down on an angle, pretty much removing the complete scar. Then wire and bring one of those side branches up to create the new top. As the branch continued to grow it will help to cover the scar.
Branches at the edge of a scar will help it to heal over more quickly.

Good luck.

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