Canon say arrived with artist (6)
I believe the answer is:
camera
'canon' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'arrived with artist' is the wordplay.
'arrived' becomes 'came' (coming is a kind of arriving).
'with' means one lot of letters go next to another.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'came'+'ra'='CAMERA'
'say' is the link.
Can you help me to learn more?
(Other definitions for camera that I've seen before include "Snapper's kit" , "TV studio item" , "Litght-proof box with a lens" , "Way of making pictures" , "Photographic equipment" .)