Crossword Genius

Quiet clue about student lacking colour (4)

Ross

I believe the answer is:

puce

I'm a little stuck... Click here to teach me more about this clue!

'colour' is the definition.
(puce is a kind of colour)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for puce that I've seen before include "Purplish colour" , "Pinkish purple" , "Shade" , "Dark red or purple-brown colour" , "Deep red to brownish purple" .)

I've seen this clue in The Daily Express.
Want a hint initially instead of a full solution? Install my app