Possible Clues:

• Clan to run in riot in dark hours?
• Ran cult on structure that's active at night
• No go in state, active at night
• Occurring at night
• Prisoner set up bout with Capone, say, happening at night
• Study picked up change almost entirely occurring at night
• Night-time criminal backing circle with Capone
• Like owls and badgers
• Night
• Number with spell in state in the small hours?