Possible Clues:

• From the air, glass oddly is a chemical weapon
• It makes people cry
• What could be great as riot controller
• March interrupter, maybe
• Lachrymator
• Weapon for police deploying a taser to protect head of government?
• It may be shot during a riot
• 'It can be used to disperse crowds (4,3)'
• Means of crowd control
• Anti-mob chemical