The term 'AMBITIOUS ONE' can be broken down into two crossword solutions: GOER (4 letters) and ASPIRER (7 letters). A goer is someone who is active and takes initiative, often going out of their way to do something. An ASPIRER is someone who has high aspirations and ambitions, and is willing to work hard to achieve them. Both terms describe someone who is ambitious and driven, and who is willing to take risks in order to reach their goals.