Faint or brief light (5)
I believe the answer is:
gleam
This clue is a double definition.
'faint' is the first definition.
(I've seen this before)
'brief light' is the second definition.
(I've seen this before)
(Other definitions for gleam that I've seen before include "Shine brightly" , "Beam of soft light, comes and goes" , "Glint" , "Coruscate" , "Look in the eye" .)