Change when course of events goes the wrong way (4)
I believe the answer is:
edit
'change' is the definition.
(edit can mean to change or alter)
'course of events goes the wrong way' is the wordplay.
'course of events' becomes 'tide' (I've seen this in another clue).
'goes the wrong way' says the letters should be written backwards.
'tide' written backwards gives 'EDIT'.
'when' acts as a link.
(Other definitions for edit that I've seen before include "modify text" , "Prepare text for publication" , "Make textual changes" , "Make alterations (in text)" , "Fix" .)