Possible Clues:

• Vehicle passes through rock in a line
• Arrangement of feet, having to stagger round vehicle
• One has four feet, is encountered in wild retreat
• Quadruped verse?
• Characters in retreat organised, having got together in a sort of line
• Move precariously around vehicle that's four feet long
• Four-footed form of vehicle to wobble about
• Move unsteadily when crossing tram lines
• Move unsteadily around vehicle in a sort of line
• I have four feet, but am unsteady around vehicle