Eye protector (5)
I believe the answer is:
visor
'eye protector' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for visor that I've seen before include "Eye protector" , "Protection for face (or against glare)" , "Helmet's face-cover" , "Part of an armour helmet" , "Transparent flap on a helmet" .)