Possible Clues:

• Sign of achievement at judo that can't be built on?
• Area round city with building restrictions
• Supposedly a no-go area for new building
• Engelbert developed land he shouldn't have?
• Engelbert performs in a protected environment!
• Area of open land around a town where building is restricted
• Gent having trouble with rebel in protected area
• Dan going openly round town
• Land where there should be no building
• It should not be built in