Cosmetic OK in woad, he gathered (9)
I believe the answer is:
eyeshadow
'cosmetic' is the definition.
(I know that eyeshadow is a type of make-up)
'ok in woad he gathered' is the wordplay.
'ok' becomes 'yes' (OK can mean yes).
'in' is an insertion indicator.
'gathered' is an anagram indicator (the letters are gathered into a new order).
'woad'+'he'='woadhe'
'woadhe' anagrammed gives 'ehadow'.
'yes' going into 'ehadow' is 'EYESHADOW'.
(Other definitions for eyeshadow that I've seen before include "cosmetic" , "beauty aid" , "application to viewers" , "used to put dark side into orbit" , "part of make-up" .)