The Clue Today's mega event
The Answer SWEARINGIN
The answer "SWEARINGIN" fits the clue "Today's mega event" because it refers to the inauguration ceremony of a new president in the United States. This event is significant and often draws a large audience, making it a "mega" occasion. During the swearing-in, the president takes an oath to uphold the Constitution, marking the start of their term in office. It's a moment of great importance for the country and its citizens.