Not in favour of retaining form of light artistic tool (6)
I believe the answer is:
crayon
'light artistic tool' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'not in favour of retaining form' is the wordplay.
'not in favour of' becomes 'con' (I can't justify this - if you can you should believe this answer much more).
'retaining' is an insertion indicator (inserted letters are held or retained).
'form' becomes 'ray' (ray is a kind of form).
'con' enclosing 'ray' is 'CRAYON'.
'of' is the link.
Can you help me to learn more?
(Other definitions for crayon that I've seen before include "Pencil of chalk or wax" , "drawer" , "Stick to colour" , "Waxy pencil" , "Drawing pen" .)