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: SONNETS 
Clue: Completes the first line of a Wordsworth poem, "Earth has not anything to show more..."
fair

Category: LITERATURE 
Clue: Poet who wrote, "Before I built a wall I'd ask to know what I was walling in or walling out"
robert frost

Category: SPORTS NICKNAMES 
Clue: Due to her specialty, Olympic swimming gold medalist Mary T. Meagher had this opera title as a nickname

madame butterfly