Commotion in prison (4)
I believe the answer is:
stir
I believe this clue is a double definition.
'commotion' is the first definition.
(stir can mean a commotion)
'prison' is the second definition.
(informal term for prison)
'in' is the link.
(Other definitions for stir that I've seen before include "Awaken" , "unrest" , "bird" , "Arouse; commotion" , "in which you'll find people with convictions" .)