Modify, as a manuscript (6)
'modify as a manuscript' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for edit that I've seen before include "Revise text" , "Tide (anag.)" , "Be in charge (of paper)" , "modify text" , "This is an act of cleaning" .)
(Other definitions for revise that I've seen before include "Change - cram" , "Memorise" , "Study for exams" , "proof" , "Go back over lesson" .)