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' anagrammed gives 'EWER'.
'to get' acts as a 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" .)