cover
罨 centers on covering something, often with a net or mesh-like structure. The meaning is straightforward and concrete.
罨 combines 罒 (net) with 奄, which likely contributes the sound and the idea of covering or enclosing. The exact historical development is uncertain.
The top 罒 is a net, and the bottom 奄 looks like a covering shape. Imagine a net being draped over something to cover it completely.
For アン, picture an ant covered by a net: ant -> アン, and the net covers the ant.