Old prison β needs this after violent breakout? (7)
I believe the answer is:
newgate
'old prison' is the definition.
(former London prison)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for newgate that I've seen before include "Stir in capital" , "Notorious 18th-century London prison" , "Old London prison" , "Prison formerly standing on site of the Old Bailey" , "London street" .)