The crossword solution for the term 'Having a key, in music' is 'tonal'. Tonality is a system of music composition that is based on a tonic note and its related chords. It is used to create a sense of musical resolution and stability, and it is the basis of most Western music. Tonality is also used to create a sense of tension and release, as well as to create a sense of movement and direction in a piece of music.