Dye then natural, to some extent (5)
I believe the answer is:
henna
'dye' is the definition.
(reddish-brown dye)
'then natural to some extent' is the wordplay.
'to some extent' says the answer is hidden in the clue.
'HENNA' is hidden in the letters of 'then natural'.
(Other definitions for henna that I've seen before include "hair colouring" , "Red hair dye" , "Reddish dye for hair etc" , "Reddish brown dye used on hair" , "A shrub, its red dye" .)