We're off to get a jug (4)
I believe the answer is:
ewer
'a jug' is the definition.
(type of vessel)
'we're off' is the wordplay.
'off' indicates anagramming the letters.
'were' is an anagram of 'EWER'.
'to get' is the link.
(Other definitions for ewer that I've seen before include "Large pitcher" , "A wide-mouthed water-jug" , "A wide-lipped jug" , "Were (anag)" , "Large water jug" .)