Related Clues:

• Nervous
• Certain craving
• Stain maker
• Niacin source
• Alkaloid in tomatoes
• Source of addiction
• Gum variety
• Ingredient in some gum
• Merit inclusion?
• Substance in cigarettes
• Smoker's stimulant
• I net coin from a popular poison
• The drug in tobacco
• Poison in tobacco
• Not nice, I change to cigarette substance