Wide-mouthed jug (4)
I believe the answer is:
'wide-mouthed jug' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ewer that I've seen before include "Jar for water" , "Jug with wide spout" , "A wide-mouthed water-jug" , "Were (anag)" , "water-carrier" .)