Some crayon or pencil (3)
I believe the answer is:
ray
'pencil' is the definition.
(I have seen 'Pencil of light ' mean 'ray' so perhaps 'pencil' could also mean 'ray')
'some crayon or' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'RAY' is hidden within 'crayon or'.
(Other definitions for ray that I've seen before include "Beam - skate" , "Beam of light or flat fish" , "Flatfish or sunbeam" , "Flat fish or sun beam" , "Sunbeam or flat fish" .)