Hair rinse (5)
I believe the answer is:
henna
'hair rinse' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for henna that I've seen before include "Red-brown dye used for body decorations" , "Natural hair dye" , "Stainer" , "Reddish dye for hair etc" , "A shrub, its red dye" .)