Possible Clues:

• What may be ridden round by one, briefly?
• Minimal transport causing college revolution
• One-wheeled pedal vehicle
• Relative catching cold -- might acrobat have one?
• Single-wheeled circus prop
• Relative admits being far from friendly with one of those taken for a ride by a clown
• Icy: uncle slipping about — hard to keep one's balance on this
• One-wheeled vehicle driven by pedalling
• One-wheeled conveyance
• Travel along a tightrope, maybe