The term 'DON GIOVANNI IS ONE' can be solved by the crossword answer 'OPERA', which is a five-letter word. OPERA is a form of musical theatre that combines music, drama, and sometimes dance. It originated in Italy during the 16th century and has since become popular around the world. Don Giovanni is an OPERA composed by Wolfgang Amadeus Mozart in 1787. It is based on the legend of Don Juan, a fictional libertine and seducer.