kind of insectivorous rodent
鼴 refers to a type of insect-eating rodent, specifically a mole-like animal. The meaning is narrow and zoological, without broader abstract extensions.
鼴 is a phono-semantic compound: 鼠 (rat, rodent) provides the meaning, while 匽 likely contributes the sound. The exact historical development is uncertain.
The left side 鼠 means rodent, and the right side 匽 looks like a hidden burrow with a sun 日 and a woman 女 inside. Picture a mole-like rodent digging a secret underground home.
For エン, imagine the rodent ending its digging at the burrow entrance: end -> エン, as the mole finishes its tunnel.