Possible Clues:

• Acid reducer, briefly
• Raising agent's protective cover outside vehicle
• Raising agent in baking (colloq.)
• Indigestion aid
• Raising agent (colloq.)
• Drivers leaving odd bric-a-brac for baker's agent
• Indigestion remedy needed, we're told, when going by car to Belgium
• Baking soda, in brief
• Antacid choice, briefly
• Relief for agita, informally