Treason not the first issue (7)
I believe the answer is:
edition
'issue' is the definition.
(edition is a kind of issue)
'treason not the first' is the wordplay.
'treason' becomes 'sedition' (I've seen this before).
'not the first' means to remove the first letter.
'sedition' with its first letter taken off is 'EDITION'.
(Other definitions for edition that I've seen before include "Number of copies printed at one time" , "Total numbers issued at one time, say of book" , "Newspaper issue" , "One version of a published text" , "single programme" .)