@darius Possible solutions I can come up with:

The surgeon is the clown's relative (wife, husband, brother, son...)The surgeon is the clown's reincarnation (or possessed by the clown's spirit)This is a town where everyone is called "Pagliacci""Pagliacci" is a title, passed on to the town's most veteran clown, who then needs to lay down their work and become clown full-time."Pagliacci" is a term for "sleepy", "drunk", or any other impairmentThis is a dream and so the rules don't matterThe son also died and this is heaven, the surgeon is the clown but surgery isn't actually necessary