Answer:

box

Answer	Crossword Clue
BOX	Pricey seating area
BOX	Jack-in-the-...
BOX	Something checked on a questionnaire

BOX	Participate in a prizefight
BOX	Crossword unit
BOX	Text ...
BOX	Trade some punches
BOX	Go a few rounds
BOX	Soccer goalie's area
BOX	Be a pugilist
BOX	Emulate Muhammad Ali

BOX	Enclosure ... and an alphabetical listing of letters not appearing elsewhere in this puzzle's answer
BOX	Engage in pugilism
BOX	Expensive seating area
BOX	Word with band or sand
BOX	Practice pugilism
BOX	Cuff
BOX	Go rounds in a ring
BOX	Kind of seat

BOX	Kind of kite
BOX	Face off in the ring
BOX	Hit like Holyfield
BOX	Spar
BOX	Present location?
BOX	Swing in a ring
BOX	Have a bout with