Article abolishing right of secular organisation (6)
I believe the answer is:
clause
'article' is the definition.
(I know that article can be written as clause)
'abolishing right of secular organisation' is the wordplay.
I cannot quite see how this works, but
'organisation' could be 'us' (U.S. is an example) and 'us' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for clause that I've seen before include "Part of a sentence with its own finite verb" , "part of legal document" , "Subdivision of a sentence" , "Grammatical division" , "Article in a contract" .)