Sash of brown, indigo tops (3)
I believe the answer is:
obi
'sash' is the definition.
(type of Japanese sash or belt)
'of brown indigo tops' is the wordplay.
'tops' says to take the initial letters.
The first letters of 'of brown indigo' is 'OBI'.
(Other definitions for obi that I've seen before include "Sash worn on Japanese kimono" , "Broad Japanese sash" , "Form of witchcraft" , "Broad sash worn with a kimono" , "magic" .)