River embankment (5)
I believe the answer is:
levee
'river embankment' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for levee that I've seen before include "An embankment built to prevent a river from overflowing" , "Morning reception once held by monarch" , "Artificial embankment" , "Early morning reception by a monarch" , "Embankment on the Mississippi" .)