Shine faintly (7)
I believe the answer is:
glimmer
'shine faintly' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for glimmer that I've seen before include "Faint wavering light" , "Flicker" , "Shine faintly with a wavering light" , "Gleam faintly, like candle in dark" , "Faint sign" .)