What does the cryptic crossword clue "Contrasts in light musical number (5,3,3)" mean?

The definition is "Contrasts in light / musical number". The wordplay uses a double definition. Double definition The answer is NIGHT AND DAY.

Contrasts in light musical number (5,3,3)

Times Cryptic #29117 | 12 Across | 2025-01-03 flower