Vessel - lacking stabilisers? (7)
I believe the answer is:
pitcher
'vessel' is the definition.
(I know that pitcher is a type of jar)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for pitcher that I've seen before include "source of drink?" , "One throwing" , "American sportsman" , "that can hold his drink" , "Baseball thrower or water jug" .)