Possible Clues:

• One of a piano trio
• Piano foot lever
• In one's depression it could have stopped a lorry
• Plead restitution for one trodden underfoot
• It gets depressed a lot
• Get around on a trike
• ''Put the ___ to the metal!''
• Over this one put one's foot down
• Foot-operated control
• Daughter wearing ring on foot?