Complex sentence: By the early 1930s, Joy was semi-retired from the motion-picture industry, but she later made several guest appearances in a few modestly-successful films, such as 1951's "Love Nest", which featured a young Marilyn Monroe.
Split into simpler sentences: By the early 1930s, Joy was in semi-retirement from the motion picture industry, but she later made several guest appearances in a few modestly successful films. One such appearance was in the 1951 release "Love Nest", which featured a young Marilyn Monroe.