The term MUSICAL BEGINNING is composed of two crossword solutions: INTRO (5 letters) and ACTI (4 letters). INTRO is short for introduction, which is the beginning of a musical piece. An introduction typically sets the tone and mood of the piece and can be instrumental or vocal. ACTI is short for activation, which is the process of bringing a musical instrument to life. Activation involves tuning the instrument, connecting it to an amplifier, and adjusting the settings.