The term 'MANY AN OFFICE HAS ONE' is solved by the crossword clue 'OATH' (4 letters). This refers to an OATH of Office, which is a formal promise made by a person upon assuming a position of authority. An OATH of Office is typically taken by elected officials, members of the military, and other public servants. It is a solemn vow to uphold the duties and responsibilities of the office and to serve the people faithfully.