since it would be very helpful to make the picture upright...

perhaps this might be better in the tree forum ...

was the tree potted or ball and burlap???

and how big is it ... no scale there..

ken

Take a spade after the leaf drop and cut around the half circle of mulch on the same side the tree is leaning.

Stake and pull back into vertical. Make sure you insulate the trunk to prevent rubbing or scaring of bark when pulling back to vertical with rope or wire.

Simple enough.

Dave

Try pulling it back over where you want it first without cutting any roots. Specimen is probably root-bound (this is common) and may not resist being adjusted as much as if it had a normal anchorage.