Silenced outside entrance to prison after one is charged (7)
I believe the answer is:
imputed
'is charged' is the definition.
(thesaurus)
'silenced outside entrance to prison after one' is the wordplay.
'silenced' becomes 'muted' (muting is a kind of silencing).
'outside' is an insertion indicator.
'entrance to' indicates taking the first letters.
'after' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
The first letter of 'prison' is 'p'.
'muted' going around 'p' is 'mputed'.
'mputed' after 'i' is 'IMPUTED'.
(Other definitions for imputed that I've seen before include "Attributed or ascribed, say a fault" , "Attributed (something bad to someone)" .)