Actually if you can look at the traditional form of this character. The upper part is "丣".“丣” work as a phonetic radical here because it is pronounced you3.
A lot of characters have been simplified in Mandarin in main land China. This make it harder for us to break down a character.
You can find more information here: 汉典解释
So the first thing to do when breaking down a character is to find its traditional version.