Can I use a section from my own arrangement of a copyright song into a new song arrangement?

I am trying to understand the copyright laws for the U.S.

Let's say I create my own sheet music arrangement of Disney's "A Whole New World" (which is copyrighted.) From what I understand, I cannot sell my arrangement or even share it for free without getting permission first.

However, let's say I like a section in my arrangement of "A Whole New World", and I want to use it in a new sheet music arrangement that is completely my own creation. Can I use it legally or not? Would the section still be under copyright?