From Longman Dictionary of Contemporary Englishno-go areaˌno-ˈgo ˌarea noun [countable] 1 SCCan area that people should not go to because it is very dangerous This part of the city was a no-go area for the police.2 TALK TO SB#a subject that cannot be discussed because it is private or because it may offend people She made it clear that her private life was a no-go area.
Examples from the Corpus
no-go area• Dartmoor in Devon was declared a no-go area, and three royal parks in London were shut to protect deer herds.• Knoydart is not exactly a no-go area but should be entered with caution.• It is Labour's only no-go area in the entire world. 