Smile brings some light (4)
I believe the answer is:
beam
I believe this is a double definition.
'smile' is the first definition.
(to beam is to smile)
'some light' is the second definition.
(beam is a kind of light)
'brings' acts as a link.
(Other definitions for beam that I've seen before include "Column of light" , "XWD SETTER" , "Rafter - smile - width" , "Ray of light or a large smile" , "Smile radiantly" .)