Bess dresses American in outfit (8)
I believe the answer is:
business
'outfit' is the definition.
(I've seen this before)
'bess dresses american in' is the wordplay.
'dresses' means one lot of letters goes inside another (dress can mean cover).
'american' becomes 'US' (United States).
'us'+'in'='usin'
'bess' enclosing 'usin' is 'BUSINESS'.
(Other definitions for business that I've seen before include "Firm" , "Work - shop" , "Trade - one's concerns or affairs" , "complicated problem" , "Commercial or industrial enterprise" .)