Push the vessel (5)
I believe the answer is:
barge
I believe this clue is a double definition.
'push' is the first definition.
(I've seen this before)
'the vessel' is the second definition.
(barge is a kind of vessel)
(Other definitions for barge that I've seen before include "River transport" , "Move roughly; boat" , "Freight vessel" , "Canal transport" , "Canal boat maybe" .)