Liquid container artist’s seen in restaurant (6)
I believe the answer is:
carafe
'liquid container' is the definition.
(carafe is a type of drinks container)
'artist's seen in restaurant' is the wordplay.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'seen in' means one lot of letters goes inside another.
'restaurant' becomes 'cafe' (cafe is a kind of restaurant).
'ra' placed inside 'cafe' is 'CARAFE'.
(Other definitions for carafe that I've seen before include "It may provide drink" , "Wine server" , "Table container for wine" , "Glass water jug" , "Bottle with a stopper, for wine or water" .)