Live to the north of a region (4)
I believe the answer is:
area
'region' is the definition.
(synonyms)
'live to the north of a' is the wordplay.
'live' becomes 'are' ('they live' means 'they are').
'to the north of' means one lot of letters go next to another (in a down clue, some letters go above others).
'are'+'a'='AREA'
(Other definitions for area that I've seen before include "field of study" , "Territory" , "Space occupied by something" , "Field -- expanse" , "part of town" .)