Restoring a single app's data from iCloud

But what if you care so much about the data on that one app that you’re willing to do a complete restore? Can you please advise how to do that? My issue is similar, but I didn’t delete the app. The data is just gone. (Just to get ahead of things, I’d appreciate no impolite comments, please—This data relates to a loved one who has passed.) Thank you respectfully in advance.

You cannot. Restoring is all or nothing.