Clifford scored one Top 20 single in the US charts in 1962, ‘Close To Cathy’. He was a nightclub singer by the age of 16, when discovered by Helen Noga, manager of Johnny Mathis. Clifford was signed to Columbia Records where he did not meet with success; but a 1962 switch to United Artists Records resulted in his biggest hit. Two follow-up singles also charted but later recordings for such labels as Cameo Records and other independent companies did not bring further success. During the 70s Clifford performed on Broadway in Grease.