Easy. Describe that person exactly as you know them without any specific, identifiable details. No names, dates, or anything else that will point directly to them.
Don’t worry that your description itself will be a ‘give-away’ because everyone sees people differently and when that person’s friends read your description, they won’t recognize their friend.
Guaranteed! I promise!
I know because it happened to me. I received the free author’s copy of a magazine with a story in it that happened to include a character based on someone I knew well at the same time that featured character and several of our mutual friends were visiting.
They all clamored to read my story and I just about died!
Until I realized that not a single person recognized the main character who was seated across the table from the reader and who, later, also read the story and did not recognize herself!
So don’t worry as long as you don’t give specifics!