Decided to keep the police out of the paper (4)
I believe the answer is:
deed
'paper' is the definition.
(thesaurus)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for deed that I've seen before include "Heroic exploit" , "A conscious action" , "Something done" , "Act - exploit - legal document" , "Document showing ownership" .)