You're heard in vessel (4)
I believe the answer is:
ewer
'vessel' is the definition.
(ewer is a type of jug)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for ewer that I've seen before include "Jug with wide spout" , "from which liquid may be poured" , "water-carrier" , "Were (anag)" , "Container" .)