Soup, cold, to take on the river (8)
I believe the answer is:
consomme
'soup' is the definition.
(consomme is a kind of soup)
'cold to take on the river' is the wordplay.
'cold' becomes 'c' (eg on taps).
'to take' is a charade indicator (letters next to each other).
'the river' becomes 'somme' (I've seen this before).
'c'+'on'+'somme'='CONSOMME'
(Other definitions for consomme that I've seen before include "Clear soup usually of beef, veal or chicken" , "starter course" , "Liquid food" , "Clear soup made with concentrated stock" , "Clear French meat soup" .)