Wide-sleeved garment in khaki — monochrome (6)
I believe the answer is:
kimono
'wide-sleeved garment' is the definition.
(type of Japanese garment)
'in khaki monochrome' is the wordplay.
'in' indicates a hidden word.
'KIMONO' is hidden within 'khaki monochrome'.
(Other definitions for kimono that I've seen before include "Jap. wrap" , "Japanese wrap" , "Traditional robe in Japan" , "Woman's loose robe, tied with a sash" , "dressing-gown" .)