bow case
籣 refers specifically to a bow case, a container for holding a bow.
籣 combines 竹 (bamboo) with 闌, which likely contributes the sound. The bamboo radical suggests a container made of bamboo, fitting the meaning of a bow case.
The top 竹 is bamboo, and the bottom 闌 looks like a gate or enclosure. Picture a bamboo gate-shaped case holding a bow: 籣 is a bow case.
For ラン, imagine a bow case made of bamboo that you run your hand along: run -> ラン, and the smooth bamboo case holds the bow.