Gleam of light (3)
I believe the answer is:
ray
This clue is a double definition.
'gleam' is the first definition.
(I've seen this before)
'light' is the second definition.
(ray is a kind of light)
'of' is the link.
(Other definitions for ray that I've seen before include "Broad flat fish; beam" , "A little light" , "Man, maybe" , "Beam; man's name" , "Man who engaged in surrealist photography" .)