鼬

Left-side rat radical - a pictograph of a long-tailed rodent, with whiskers and clawed feet. Indexes 鼬 in the small-mammal family alongside 鼯 flying squirrel and other rodent-like animals. The radical groups weasels with rodents because pre-modern Chinese natural history filed all small fanged scurrying mammals under the same heading.

Right side 由 supplies the sound: yóu shifted to yòu with tone change. 由 itself shows a sprout pushing out of a field - imagery that doesn't transfer. Borrowed purely as a sound marker for the weasel's name. Same family: 油 oil, 抽 to pull out, 笛 flute, all sharing this phonetic.