The term MUSICAL KNACK can be broken down into two crossword solutions: EAR (3 letters) and MUSICAL (8 letters). EAR refers to the sense organ that is responsible for hearing, which is essential for MUSICAL ability. MUSICAL is an adjective that describes someone or something with a natural aptitude for music. Therefore, MUSICAL KNACK can be defined as a natural talent for music, which is often developed through practice and experience.