Possible Clues:

• Wide part of foot caught by light immobilising device
• Ring for motoring press to stop drivers in their tracks
• Take action against wrongly parked car with part of boot against back of traffic light?
• Immobilise a car
• Calm help we required to move this encumbrance
• Help me claw off what's clinging and won't let me go
• Device to immobilise illegally parked vehicle
• We help calm Dicky Parker's dread
• Illegal parking restriction