Reporter’s right to obstruct suspected adulterer (13)
I believe the answer is:
correspondent
'reporter's' is the definition.
(I've seen this before)
'right to obstruct suspected adulterer' is the wordplay.
'right' becomes 'r' (abbreviation).
'to obstruct' means one lot of letters goes inside another (inserted letters interrupt or obstruct the word).
'suspected adulterer' becomes 'co-respondent' (someone accused of committing adultery in court).
'r' put inside 'corespondent' is 'CORRESPONDENT'.
(Other definitions for correspondent that I've seen before include "Reporter on specialist areas" , "Overseas journalist" , "Journalist; letter-writer" , "Pen-friend" , "Journalist; letter writer" .)