Novel, opening in old British prison (7)
I believe the answer is:
newgate
'old british prison' is the definition.
'Newgate' can be an answer for 'prison' (I've seen this before). I am unsure of the 'old british' bit.
'novel opening' is the wordplay.
'novel' becomes 'new' (novel means new or fresh).
'opening' becomes 'gate' (a gate is an opening or entrance).
'new'+'gate'='NEWGATE'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for newgate that I've seen before include "Prison formerly standing on site of the Old Bailey" , "Old Nick" , "London street" , "Stir in capital" , "Old London prison" .)