The term 'CALLS UPON' can be broken down into four separate crossword solutions: ENLISTS (7 letters), ASKS (4 letters), VISITS (6 letters), and TURNSTO (7 letters). Enlisting is the process of formally enrolling in a military service, while asking is the act of posing a question or request. Visiting is the act of going to a place for a short period of time, and turnsto is an archaic term meaning to appeal to someone for help or advice. Together, these four words can be used to describe the action of calling upon someone for assistance.