A married girl in the USA (7)
I believe the answer is:
america
'the usa' is the definition.
(synonyms)
'a married girl' is the wordplay.
'married' becomes 'm' (abbreviation, e.g. in genealogy).
'girl' becomes 'erica' ().
'a'+'m'+'erica'='AMERICA'
'in' acts as a link.
(Other definitions for america that I've seen before include "huge landmass" , "North or South, it's a continent" , "West Side Story song" , "Continent named after Vespucci" , "Western land mass" .)