Officer reportedly given powerless role in contact sport (7,3)
I believe the answer is:
martial art
'contact sport' is the definition.
(I've seen this before)
'officer reportedly given powerless role' is the wordplay.
'officer' becomes 'marshal' (I've seen this before).
'reportedly' shows a homophone (sound like).
'given powerless role' becomes 'art' (I can't explain this - if you can you should believe this answer much more).
'marshal' is a homophone of 'martial'.
'martial'+'art'='MARTIAL ART'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for martial art that I've seen before include "for which war paint could be used?" , "Contact sport" , "Skilled defence" , "combative sport" , "As a form of self-defence" .)