Issue could be treason, having killed leader (7)
I believe the answer is:
edition
'issue' is the definition.
(edition is a kind of issue)
'treason having killed leader' is the wordplay.
'treason' becomes 'sedition' (sedition is treason against a government or ruler).
'having killed leader' means to remove the first letter (the first letter is removed or killed).
'sedition' with its initial letter removed is 'EDITION'.
'could be' is the link.
(Other definitions for edition that I've seen before include "(Copy from) single print run" , "in printed form" , "Total number of copies issued (of book)" , "Version of a publication" , "Particular version of a published text" .)