parsley
芹 refers specifically to parsley, a leafy herb used in cooking.
芹 combines the grass radical 艹 with 斤, which likely contributes a phonetic element. The character originally referred to a type of water dropwort or parsley-like plant.
The grass radical 艹 sits above 斤, like parsley growing in a garden bed. Think of 斤 as a garden plot marker, and 艹 as the parsley leaves sprouting above.
For キン, imagine a king (キン) who demands fresh parsley on every dish. The king's insistence on parsley ties the sound キン to the herb.
Java water dropwort (Oenanthe javanica); Japanese parsley
parsley (Petroselinum crispum)
mitsuba (Cryptotaenia japonica); Japanese honewort; Japanese honeywort; Japanese chervil; Japanese parsley
Mackenzie's water hemlock (Cicuta virosa)
Cnidium japonicum (species of umbellifer)
(giving a) small present; trifling gift
Chinese celery; leaf celery