Just William's colour (5)

I believe the answer is:

brown

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

'colour' is the definition.
(brown is a colour)

I can't explain the rest of the clue.

(Other definitions for brown that I've seen before include "Fry in a pan until it changes colour" , "Former PM" , "Chocolate, perhaps" , "Labour PM, b. 1951" , "It is used for wrapping" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app