Related Clues:

• Lilac, e.g.
• See 25-Across
• Stink
• Carbon monoxide's lack
• Lead for a Lab
• Reason to ask 'What's cookin'?'
• Whiff
• Kind of therapy
• It may be left in a locker
• Garlic, for one
• Sure target
• Pervasive quality
• Fungus byproduct
• Aura
• Something the nose knows