to enter, to make progress, to advance, to urge forward
乵 centers on forward movement: entering a space, making progress, advancing, or urging someone onward.
乵 is a rare character whose exact historical development is uncertain. It visually combines 辛 and 乚, but the original semantic and phonetic roles of these components are not clearly established.
The left side 辛 can suggest hardship, and the right side 乚 looks like a hook pulling forward. Imagine using a hook to pull yourself through a difficult entrance, advancing step by step.
For エン, picture entering a yen shop (en) to urge the clerk forward: en -> エン, and you make progress inside.