Shine at midnight? Rubbish! (7)
I believe the answer is:
glitter
'shine' is the definition.
('glitter' can be a synonym of 'shine')
'midnight? rubbish' is the wordplay.
'midnight?' becomes 'g'.
'rubbish' becomes 'litter' (litter is a kind of rubbish).
'g'+'litter'='GLITTER'
'at' acts as a link.
(Other definitions for glitter that I've seen before include "Are bright" , "Flashiness" , "Show some sparkle" , "Decorative sparkle" , "Glisten, sparkle" .)