The term 'SUPERB SERVE' can be broken down into two crossword solutions: ACE (3 letters) and SUPERB (7 letters). ACE is a term used in tennis to describe a serve that is so powerful and accurate that the opponent cannot return it. It is also used in other sports such as badminton and volleyball. SUPERB is an adjective meaning excellent or outstanding. Therefore, the phrase 'SUPERB SERVE' could be used to describe a serve in tennis that is both powerful and accurate.