Vicinity with princes mixing outside court (9)
I believe the answer is:
precincts
'vicinity' is the definition.
(thesaurus)
'princes mixing outside court' is the wordplay.
'mixing' indicates an anagram.
'outside' indicates putting letters inside (some letters go outside others).
'court' becomes 'ct' (abbreviation used in road names).
'princes' with letters rearranged gives 'precins'.
'precins' going around 'ct' is 'PRECINCTS'.
'with' acts as a link.
(Other definitions for precincts that I've seen before include "surroundings" , "City districts" .)