Reportedly split part of gun (6)
I believe the answer is:
breech
'gun' is the definition.
(thesaurus)
'reportedly split' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'split' becomes 'breach' (I've seen this before).
'breach' is a homophone of 'BREECH'.
'part of' is the link.
(Other definitions for breech that I've seen before include "part of Winchester" , "Lower part of a gun" , "Rear part of rifle" , "Bit of gun" , "Rear opening to a gun barrel" .)