Interest in business (7)
I believe the answer is:
concern
This clue is a double definition.
'interest' is the first definition.
(concern is a kind of interest)
'business' is the second definition.
('concern' can be a synonym of 'business')
'in' is the link.
(Other definitions for concern that I've seen before include "Involve" , "Affair" , "Business organisation" , "Relate to; care" , "Disquiet" .)