Possible Clues:

• Ponder gearwheel — it corroded
• Think company will have special appeal amongst spectators
• Think about old barrier involving it
• Contemplate deeply
• THINK
• Consider disembowelled dog from foreign museum
• Think of a tooth: it took food
• Think about old barrier about sex
• Dwell on bar with one major exhibitor in London
• Think about nothing, then stir to depose leader