Something sparkling captured by astronaut in selfie (6)
I believe the answer is:
tinsel
'something sparkling' is the definition.
'captured by astronaut in selfie' is the wordplay.
'captured by' indicates the answer is hidden within the clue.
'TINSEL' can be found hidden inside 'astronaut in selfie'.
(Other definitions for tinsel that I've seen before include "Enlist the glittering decoration" , "Cheap and gaudy metallic material" , "Listen (anag) - something cheap and showy" , "23 across (anag)" , "Cheap shiny stuff" .)