to earn, to make a profit
贃 centers on gaining financial benefit: earning money or making a profit through effort or trade.
贃 combines 貝 (shell, money) with 患, which likely contributes the sound. The structure suggests a phono-semantic compound related to money or profit, but the exact historical development is uncertain.
The left side 貝 represents money or shells used as currency. The right side 患 looks like a person burdened with worries. Picture someone worrying about money, but then finding a way to earn a profit and relieve that concern.
For ワン, imagine earning one (ワン) big profit after a long day of work: one -> ワン, and the money 貝 comes rolling in.