Shed reportedly used for lavatory, commonly (6)
I believe the answer is:
throne
'for lavatory commonly' is the definition.
(throne can informally mean a toilet)
'shed reportedly' is the wordplay.
'shed' becomes 'thrown'.
'reportedly' indicates a 'sounds like' (homophone) clue.
'thrown' is a homophone of 'THRONE'.
'used' acts as a link.
(Other definitions for throne that I've seen before include "Royal chair" , "Royalty sits on it" , "Sovereign's seat" , "Chair of state" , "A king or queen sits on it" .)