Paint swatch option (3)
I believe the answer is:
hue
'paint swatch option' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for hue that I've seen before include "Delicate shade" , "Tint, shade" , "Tone, shade" , "Shade of colour; Vietnam port" , "red or black, say" .)