basin, container for wine
匜 centers on a container for holding liquid: a basin or a vessel for wine. The two meanings are closely related as types of liquid-holding containers.
匜 combines the enclosure 匚, representing a container, with 也 inside, which likely contributes a phonetic element. The character originally referred to a type of vessel used for pouring liquids, such as a basin or wine container.
The outer 匚 is a box or container, and inside is 也, which looks like a pouring spout. Imagine a basin with a spout for pouring wine.
For イ, picture an eagle (イーグル) using the basin to hold its wine: eagle -> イ, and the bird enjoys a drink from the container.