Possible Clues:

• The doubt the dampness of the fog may bring to the iron (8)
• Spray against corrosion you have no confidence in
• Suspicion condensation leads to corrosion
• Suspect the motorway's getting done up, we hear
• Suspect in red coat visible behind haze
• You can't depend on it when there's decay caused by fog
• Is the decay caused by fog? You can;t depend on it
• Suspect damp with decay
• Have doubts about water vapour and what it may produce
• Be wary of the decay that fog causes, it seems