… affected American college centre (6)
I believe the answer is:
campus
'college centre' is the definition.
(site of a college or university)
'affected american' is the wordplay.
'affected' becomes 'camp' (I've seen this before).
'american' becomes 'us' (abbreviation for United States).
'camp'+'us'='CAMPUS'
(Other definitions for campus that I've seen before include "University buildings and grounds" , "academic haunt" , "educational location" , "College estate" , "Area around a university" .)