Maybe If you airlayer the top..
View attachment 534993
and regrow it
View attachment 534995
Then the pot will fit
It is a bit drastic option, and will take some time, but keep in mind that you could improve the tree and sell the airlayer too
Probably you already have seen this one from
sidiao webpage
View attachment 534996
For me it is the perfect combination between a tidy and natural ramification for an elm.
Cheers