Bess keeps us in trade (8)
I believe the answer is:
business
'trade' is the definition.
(I've seen this before)
'bess keeps us in' is the wordplay.
'keeps' is an insertion indicator.
'us'+'in'='usin'
'bess' placed around 'usin' is 'BUSINESS'.
(Other definitions for business that I've seen before include "Trade - one's concerns or affairs" , "Commercial or industrial enterprise" , "Firm" , "Commerce, trade" , "Affair - matters to be attended to" .)