Gathering at Embankment (5)
I believe the answer is:
levee
I believe this is a double definition.
'gathering' is the first definition.
(thesaurus)
'embankment' is the second definition.
(I've seen this before)
'at' acts as a link.
(Other definitions for levee that I've seen before include "Embankment on the Mississippi" , "protection for bank" , "Riverside embankment" , "Retaining embankment" , "Flood embankment" .)