This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鍈 combines 金 (metal) with 英, which likely contributes the sound. The exact historical development is uncertain.
The left side is metal 金, and the right side is 英 (a shape associated with excellence or flower). Without a clear meaning, picture a rare metal ornament shaped like a flower.
For エイ, imagine a metalworker named A who crafts this rare kanji: A -> エイ, and the metal 金 component ties to the craft.