Reformed deist prepares text (5)
I believe the answer is:
edits
'prepares text' is the definition.
(I've seen this in another clue)
'reformed deist' is the wordplay.
'reformed' is an anagram indicator.
'deist' with letters rearranged gives 'EDITS'.
(Other definitions for edits that I've seen before include "Checks" , "Alters (text)" , "Puts together" , "Makes changes to text" , "Proofreads" .)