First attempts at cleaning can be, um, disappointing. And irreversible. So before risking your coin, PRACTICE cleaning another similar-condition coin. My Suggestion: Don't clean it. Instead, put your coin as-is into an air-tite capsule (A19). And if you ever want to display it: https://www.air-tites.com/LH_MF_Holders.html#.W6dLeGeWzX5
I've used acetone and xylene from the hardware store; a good soak with maybe a Qtip under the fluid lightly may be a solution.