Editing process changed "ultimately" to "primarily" (3)
I believe the answer is:
cut
'editing' is the definition.
(cut is a kind of editing)
'changed ultimately to primarily' is the wordplay.
'primarily' says to take the initial letters.
The initial letters of 'changed ultimately to' is 'CUT'.
'process' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for cut that I've seen before include "Gash" , "Stop filming" , "Reduction in power" , "Reduction; piece of meat" , "Slight" .)