Flood puts bear in river (6)
I believe the answer is:
deluge
'flood' is the definition.
(I know that flood can be written as deluge)
'bear in river' is the wordplay.
'bear' becomes 'lug' (both can mean to carry around).
'in' indicates putting letters inside.
'river' becomes 'Dee' (River Dee).
'lug' put within 'dee' is 'DELUGE'.
'puts' acts as a link.
(Other definitions for deluge that I've seen before include "Major flood" , "A heavy downpour of rain" , "Inundation" , "A heavy fall of rain (6)" , "Severe flood" .)