Artist may use this light in study (6)
I believe the answer is:
crayon
'artist may use this light in study' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'light in study' is the wordplay.
'light' becomes 'ray' (ray is a kind of light).
'in' indicates putting letters inside.
'study' becomes 'con' (con can informally mean to study).
'ray' inserted into 'con' is 'CRAYON'.
Can you help me to learn more?
(Other definitions for crayon that I've seen before include "Drawing-stick" , "Child's colouring stick" , "drawer" , "Drawing implement" , "Waxy pencil" .)