College grounds affected American (6)
I believe the answer is:
campus
'college grounds' is the definition.
(university or college site)
'affected american' is the wordplay.
'affected' becomes 'camp' (camp can mean exaggerated or affected).
'american' becomes 'US' (United States).
'camp'+'us'='CAMPUS'
(Other definitions for campus that I've seen before include "Area around a university" , "University estate" , "University buildings and grounds" , "University premises" , "University location" .)