A married woman’s vast place across the pond (7)
I believe the answer is:
'vast place across the pond' is the definition.
('across the pond' can mean across the Atlantic)
'a married woman's' is the wordplay.
'married' becomes 'm' (abbreviation, e.g. in genealogy).
'woman' becomes 'erica' ().
(Other definitions for america that I've seen before include "'Country named after Vespucci, Italian navigator (7)'" , "Curious camera I take to the continent" , "Race aim (anag)" , "Country bordering Mexico" , "Western land mass" .)