Clara was born in Trier in 1860. Her father was a Prussian civil servant. When she was 8 years old, she moved to Düsseldorf where she attended school.
Clara moved to Berlin with her mother when she was twenty. She married a Jewish publisher Fritz Theodor Cohn in 1896. The year after she began her successful career as a writer. Her first book was published in 1897.
In 1933, She published a book condemning the Weimer Republic. It was forbidden by the Third Reich because her husband was Jewish.
She moved to Brazil in 1937 for a year but returned to Nazi Germany. Her works were praised not only by the press but the Nazis as well. The book, "Dormant Army" was the first Volksdeutsche novel praised by Nazi critics.