Gleam, shimmer (7)
I believe the answer is:
glisten
This clue is a double definition.
'gleam' is the first definition.
(I know that gleam can be written as glisten)
'shimmer' is the second definition.
(I know that shimmer is a kind of glisten)
(Other definitions for glisten that I've seen before include "Be a shining example" , "Reflect" , "'Shine, as if wet (7)'" , "look bright" , "Glow from reflection" .)