Image not left by author's protection (9)
I believe the answer is:
copyright
'author's protection' is the definition.
(I've seen this in another clue)
'image not left by' is the wordplay.
'image' becomes 'copy' (I can't explain this - if you can you should give a lot more credence to this answer).
'not left' becomes 'right' ('right' is the opposite to 'left').
'by' means one lot of letters go next to another.
'copy'+'right'='COPYRIGHT'
Can you help me to learn more?
(Other definitions for copyright that I've seen before include "Legal control of literary or artistic work" , "property of the author?" , "Protection for writer" , "Protected" , "Document granting exclusive right to publish" .)