This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 斳 is uncertain. It appears to combine 堇 and 斤, but the original semantic and phonetic roles are unclear.
Since the meaning is unclear, focus on the shape: 堇 (clay) on the left and 斤 (axe) on the right. Picture an axe cutting clay, but remember this is just a visual mnemonic, not a real meaning.
For キン, imagine a king (キン) using an axe (斤) to shape clay (堇). The king's axe cues キン.