Expert; colour (4)
I believe the answer is:
buff
I believe this clue is a double definition.
'expert' is the first definition.
(buff can mean an expert or aficionado)
'colour' is the second definition.
(I know that buff is a type of brown)
(Other definitions for buff that I've seen before include "Dull yellow" , "Polish - one's bare skin" , "Polish; expert, devotee" , "Polish - light colour - expert" , "Sandy colour - bare skin" .)