Maroon fibre (6)
I believe the answer is:
strand
I believe this clue is a double definition.
'maroon' is the first definition.
('strand' can be a synonym of 'maroon')
'fibre' is the second definition.
(strand is a kind of fibre)
(Other definitions for strand that I've seen before include "string" , "Drive aground; thread" , "A thread or a beach" , "Stretch of sand" , "Maroon - thread" .)