Having left at some stage, he may be back in jug (3)
I believe the answer is:
lag
This clue could be a double definition.
'having left at some stage he may be back' is the first definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'jug' is the second definition.
(synonyms)
'in' acts as a link.
Can you help me to learn more?
(Other definitions for lag that I've seen before include "Insulate (pipes)" , "Loiter" , "trail" , "Drag one's feet" , "Fall behind with gal" .)