Related Clues:

• Circle lines
• Cuts into a pie, often
• Drops a line
• They're sometimes right, but never wrong
• Lines in a circle
• They go straight in a circle
• Finagler's concerns
• They're half the diameter
• Shadows on an equatorial sundial, say
• Halves of diameters
• r's, in math
• They start in the middle
• Semi-diameters
• Parts of forearms
• They're all right in squares