This was once the name of a famous athlete (I apologize in advance for the choppiness of this puzzle: 2-letter words, single letters just hanging in space, obscure words, etc., etc., etc. Sorry!)
Hint: Sometimes a boxer is told to go to their corner
Reveal: There is a boxer (pugilist) hidden in each 3x3 corner of the grid: Starting at 1A and going clockwise it spells DELAHOYA (Oscar) inside of De La Hoya is the letter C. Starting 12A it spells MUHAMMAD (Ali) inside is the letter L. 61A ROBINSON (Sugar Ray) inside is A. 64A MARCIANO (Rocky) inside is Y. CLAY is the former name of Muhammad Ali.