Stick a duck into a vessel! (5)
I believe the answer is:
canoe
'a vessel' is the definition.
(canoe is a kind of vessel)
'stick a duck into' is the wordplay.
'stick' becomes 'cane' (cane is a kind of stick).
'a duck' becomes 'o'.
'into' indicates putting letters inside.
'cane' going around 'o' is 'CANOE'.
(Other definitions for canoe that I've seen before include "Primitive boat" , "Ocean (anag)" , "River craft" , "Small and light boat, pointed at both ends" , "Boat that's paddled" .)