Cosmetic — half made to cover a blemish (7)
I believe the answer is:
mascara
'cosmetic' is the definition.
(mascara is a kind of cosmetic)
'half made to cover a blemish' is the wordplay.
'half made' becomes 'ma'.
'to cover' is an insertion indicator.
'blemish' becomes 'scar' (scarring is a kind of blemishing**).
'a'+'scar'='ascar'
'ma' enclosing 'ascar' is 'MASCARA'.
(Other definitions for mascara that I've seen before include "facial cosmetic" , "black application" , "Maracas (anag.)" , "that accentuates lashes" , "Eyelash make-up" .)