Prison riot (4)

I believe the answer is:

stir

I believe this is a double definition.

'prison' is the first definition.
(informal term for prison)

'riot' is the second definition.
(I've seen this before)

(Other definitions for stir that I've seen before include "Agitation - prison" , "Mix the ingredients" , "Commotion - prison" , "Sensation" , "Big house" .)

I've seen this clue in The Telegraph.

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