Correct XAML pattern to bind element to BindingContext property ('x:Name' binds to page not context)

Hi, I'm new to Xamarin, but I've already built a few pages and have got most of the binding working flawlessly.
I am, however, having an issue figuring out the proper way to bind an element in XAML (a Map to be precise) to a child property of the BindingContext (a ViewModel). I see that the "x:Name" attribute will bind it to a property of the page class, but not the context. All the other binding examples affect values of an element, but not the element object itself.
Is there a way to do this cleanly, or do I have to do what I'm doing now where the page class passes the element (Map) along into the ViewContext manually at startup?