Possible Clues:

• Ineffective medication
• Fasten lead round old dummy?
• RC vespers; inactive pill
• It will do no harm to think it does good, so put it first (7)
• That's where it starts to be harmless before the river goes the wrong way
• Control situation, cutting short expression of dissatisfaction
• Pill with no medicinal content
• Harmless substance as medicine to sooth patient
• Put unpleasant smell into ineffective medicine
• Part of a test, maybe