earth-carrying basket
簣 refers to a basket used for carrying earth, a specific tool for moving soil or dirt.
簣 combines 竹 (bamboo) with 貴, which likely contributes the sound. The bamboo top suggests a basket made from bamboo strips, fitting the meaning of an earth-carrying basket.
The bamboo top 竹 over 貴 suggests a valuable basket woven from bamboo, used to carry precious earth.
For キ, imagine a key-shaped basket: key -> キ, and you use this key-like basket to carry earth.
to fail one step short of great success; to fall at the last hurdle