Related Clues:

• Northern university students, void
• and void
• No longer enforceable
• Word on a check that's no good anymore
• Deep space, basically
• Like sets with no elements
• Null and
• Nursed, taking time off, finished
• Doubly invalid
• Double space?
• Render null
• Cancellation stamp word
• Died; elapsed
• Finished up in crowded neighbourhood
• All wrapped up