Related Clues:

• Empty talk
• Roadside sign
• Talk idly
• Energy source
• Driver's need
• Stove option
• Burn it by stepping on it
• Windbag's output
• Balloon contents
• Racer's sponsor
• Its slogan is 'The Racer's Edge'
• Petrol
• Filling-station supply
• Bombas-tic talk
• 21-Across, for one