Possible Clues:

• Rowing team, e.g
• Foursome times two
• Sculls in a quad scull, e.g
• One's pawns on a chessboard, e.g.
• Quarterfinals complement, e.g.
• Oars in a quad scull, e.g.
• Oxygen atom's protons, e.g.
• Sliced pizza, often
• Series of eight
• Rowing team, e.g.