Possible Clues:

• "The Queen's Gambit" game
• That fellow’s blocking Civil Service game
• Label once home to Bo Diddley, Muddy Waters etc.
• Its openings are often studied
• What he's playing on board with hundreds around
• Does this end with mating?
• Knight's activity?
• Revolutionary's singular aim here is to overthrow king
• Game with knight moves
• She worked in the civil service game