Can there's a root wrapped around the base of my tree be fixed without removing the tree?

Often, if caught before the root has flattened the stem. The procedure is root collar excavation — soil carefully removed from the base, usually with compressed air so remaining roots are not damaged — followed by cutting out the offending root. Practitioner guidance favors intervening while the girdling root is still small relative to the trunk and has not fused into it (specific diameter thresholds vary by source and are UNVERIFIED here). Once the root has grown into the stem, removing it takes a large share of the remaining live tissue with it and the cure can be worse than the condition; at that stage the honest recommendation is often to accept a shortened lifespan and plan a replacement. A tree already showing one-sided canopy decline has been girdled for a long time.