Twinkle, sparkle (11)
I believe the answer is:
scintillate
This clue is a double definition.
'twinkle' is the first definition.
(synonyms)
'sparkle' is the second definition.
(to scintillate is to sparkle or gleam)
(Other definitions for scintillate that I've seen before include "Emit flashes of light" , "give sparkling performance" , "Twinkle - sparkle" , "Coruscate" , "Glitter" .)