Answer: initiator

AnswerCrossword Clue
INITIATORBeginner.
INITIATORStarter.
INITIATORHe's always starting something.
INITIATORPrime mover
INITIATORCatalyst
INITIATORFirst-move maker
INITIATORSpark provider
initiatorto begin
initiatorto admit into membership
initiatorone who initiates
initiatorto instruct in some subject