Possible Clues:

• 'Region of space from which nothing can escape (5,4)'
• Result of a star's collapse
• There's no escaping this
• Trunk full of powdered chalk in prison
• What one sees at night on golf course is a problem for some stars
• Term popularized by physicist John Wheeler
• What one sees at night on golf course is the final resting place for some stars
• British miss spot where star used to appear
• Coal mine, perhaps?
• Subject for Stephen Hawking