The crossword solution for the term 'SONNY's Singing Partner' is Cher, a four-letter word. Cher is an American singer, songwriter, actress, and television personality who rose to fame in 1965 as half of the pop duo SONNY & Cher. The couple had several hit singles, including 'I Got You Babe' and 'The Beat Goes On'. They also starred in their own variety show, The SONNY & Cher Comedy Hour, which ran from 1971 to 1974.