Possibly partial provision for light protection (5)
I believe the answer is:
visor
'protection' is the definition.
(visor is a kind of protection)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for visor that I've seen before include "Movable front part of helmet" , "Transparent flap on a helmet" , "Mask" , "Sunshade" , "Helmet's face-cover" .)