Top detective's first admitting copper's charged (7)
I believe the answer is:
accused
'charged' is the definition.
('accuse' can be a synonym of 'charge')
'top detective's first admitting copper's' is the wordplay.
'top' becomes 'ace'.
'detective's first' becomes 'd' (1st letter of 'detective').
'admitting' is an insertion indicator.
'copper's' becomes 'cu's' (chemical symbol).
'ace'+'d'='aced'
'aced' enclosing 'cus' is 'ACCUSED'.
(Other definitions for accused that I've seen before include "Person being charged" , "Defendant appearing on a criminal charge" , "Blamed" , "The person in the dock" , "Charged with an offence" .)