Possible Clues:

• Throuple, say
• Excursion not quiet - notice three making a sound?
• It includes a third and a fifth
• "Charlie's Angels" are one
• Time to organise raid to expose criminal gang
• Elementary chord
• Chord one gets in a type of jazz
• First person in jazz to make three-note chord
• Three-note chord — Chinese criminal gang
• A, C and E, on a piano