Possible Clues:

• Device that's "fed"
• Parking accessory with cops needing hesitation
• Parking post
• Inanimate object that has to be fed
• Postage source
• 'Take it as read to have a date with 'er, by the sound of it (5)'
• Object 'fed' when parking
• Measuring device agreed with every reading initially
• Measurement slightly more than a yard
• Electrical reading device