Churned up salted deposits at river mouths (6)
I believe the answer is:
deltas
'river mouths' is the definition.
'churned up salted' is the wordplay.
'churned up' indicates anagramming the letters.
'salted' is an anagram of 'DELTAS'.
'deposits at' is the link.
(Other definitions for deltas that I've seen before include "Triangular land patches at river mouths" , "Triangular areas where rivers divide before entering the sea" , "some flowers form them" , "Coastal features" , "Final sections of River" .)