Criminal upset getting old inside prison (4)

I believe the answer is:

gaol

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'prison' is the definition.
(thesaurus)

'criminal upset getting old inside' is the wordplay.
'criminal upset getting' becomes 'ga' (I can't justify this - if you can you should believe this answer much more).
'old' becomes 'cold' ('cold' can be a synonym of 'old').
'inside' indicates the central letters.
The central letters of 'cold' are 'ol'.
'ga'+'ol'='GAOL'

Can you help me to learn more?

(Other definitions for gaol that I've seen before include "Prison (British spelling)" , "stir" , "Nick" , "See 1" , "The Ballad of Reading -- (Wilde)" .)

I've seen this clue in The Telegraph.

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