Janet Reno was the late Attorney General of the United States, serving from 1993 to 2001. She was the first woman to hold the position and the longest-serving Attorney General in U.S. history. Her tenure was marked by a number of high-profile cases, including the Waco siege and the Elian Gonzalez case. Her last name is Reno, which is a four-letter word that can be used to answer the crossword clue.