Bare soak doing the backstroke in river (6)
I believe the answer is:
expose
'bare' is the definition.
(bare can mean to expose or reveal)
'soak doing the backstroke in river' is the wordplay.
'soak' becomes 'sop' (dip food in liquid).
'doing the backstroke' shows that the letters should be reversed in order.
'in' indicates putting letters inside.
'river' becomes 'exe' (River Exe).
'sop' backwards is 'pos'.
'pos' inserted into 'exe' is 'EXPOSE'.
(Other definitions for expose that I've seen before include "Unmask or denounce" , "Make visible or apparent" , "Lay open, reveal" , "article on scandal?" , "Show up" .)