Jug of porridge! (4)
I believe this clue is a double definition.
'jug' is the first definition.
(both are slang for prison)
'porridge?' is the second definition.
(both are slang terms for prison)
'of' acts as a link.
(Other definitions for stir that I've seen before include "What keeps those inside" , "Produce disorder < , wake up" , "Excitement" , "Detention centre" , "Whisk or make a move" .)
This clue is a double definition.
'jug' is the first definition.
(jug can informally mean a prison)
'porridge' is the second definition.
(British slang)
'of' acts as a link.
(Other definitions for prison that I've seen before include "Place of detention for criminals" , "Slammer" , "Jail" , "Eg, Wormwood Scrubs" , "Place of confinement" .)