Rush into the boat (5)
I believe the answer is:
barge
This clue is a double definition.
'rush' is the first definition.
(barging is a kind of rushing)
'the boat' is the second definition.
(barge is a kind of boat)
'into' acts as a link.
(Other definitions for barge that I've seen before include "Push - boat" , "Violently push" , "Possibly lighter" , "force" , "Canal boat maybe" .)