Possible Clues:

• Line from one corner to the fartherst one
• A straight line joining two opposite corners
• Line connecting two nonadjacent corners of a rectangle
• At a slant
• Crooked Democrat's in gaol with a criminal
• Like Broadway's course
• Sloping line
• Straight line joining any two non-adjacent corners of a polygon
• Line taken by bishop when villain invades land taken back
• Bishop's chess line