Annoyed editor changed sides (7)
I believe the answer is:
crossed
'changed sides' is the definition.
The definition and answer can be both to do with motion as well as being past participle verbs.
Maybe you can see an association between them that I don't see?
'annoyed editor' is the wordplay.
'annoyed' becomes 'cross' (cross can mean angry).
'editor' becomes 'ed' (abbreviation).
'cross'+'ed'='CROSSED'
Can you help me to learn more?
(Other definitions for crossed that I've seen before include "Went over to the other side" , "Traversed" , "Came over and < annoyed" , "Passed" , "Intersected; opposed" .)