Rousing prison group (8)
I believe the answer is:
stirring
'rousing' is the definition.
(stirring is a kind of rousing)
'prison group' is the wordplay.
'prison' becomes 'stir' (informal term for prison).
'group' becomes 'ring'.
'stir'+'ring'='STIRRING'
(Other definitions for stirring that I've seen before include "Arousing strong feeling" , "causing trouble" , "Heady" , "Agitating or rousing" , "Agitating a liquid" .)