You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: U.S. PRESIDENTS 
Clue: He was the last man elected president who had served as a U.S. Senator
richard m. nixon

Category: FILM LEGENDS 
Clue: His only competitive Oscar win was for Best Score in 1973 for a 1952 film in which he had starred as a washed-up comic
charlie chaplin

Category: WORD & PHRASE ORIGINS 
Clue: This term was first used in an ice cream trade journal in 1937; it began to appear in the nuclear power industry in the '60s

meltdown