Depressed about river in flood (5)
I believe the answer is:
drown
'flood' is the definition.
(thesaurus)
'depressed about river' is the wordplay.
'depressed' becomes 'down' ('down' can be a synonym of 'depressed').
'about' is an insertion indicator.
'river' becomes 'r'.
'down' placed around 'r' is 'DROWN'.
'in' acts as a link.
(Other definitions for drown that I've seen before include "Flood; kill" , "Go under" , "Die by immersion in liquid" , "Die in water" , "Flood (an area)" .)