bank
漘 centers on the edge where water meets land: a bank or shore. The single given meaning is a straightforward geographical feature.
漘 combines 氵 (water) with 脣, which likely provides the sound and relates to the edge or lip of something, together suggesting the water's edge or bank.
Water 氵 meets the lip-like edge 脣 of the land: that meeting point is the bank.
For シン, imagine the shin of a person standing at the water's edge, where the bank meets the water: shin -> シン.