Possible Clues:

• Measure of a running back's gains
• How the vehicle turns overtime to measure?
• A German standing in for one in criminal court employment?
• By the three foot length, that's how old the enclosure is
• The elderly admitting dreadful drag covers a measured area
• I'm surprised beam retrieved, given length
• Ready to move round silver, given cost of storing
• Distance driven in police time?
• Distance in three-foot units
• Gain or loss