Deny wife is held in old prison (7)
I believe the answer is:
newgate
'old prison' is the definition.
(former London prison)
'deny wife is held' is the wordplay.
'deny' becomes 'negate' (I've seen this before).
'wife' becomes 'w'.
'is held' indicates putting letters inside.
'negate' placed around 'w' is 'NEWGATE'.
'in' acts as a link.
(Other definitions for newgate that I've seen before include "Old London prison" , "London street" , "Former London prison" , "prison long ago" , "Old Nick" .)