The very bright edges of earring and garish extra decorations (8)
I believe the answer is:
eggheads
'decorations' is the definition.
Although both the answer and definition are plural nouns, I can't understand how one could define the other.
I cannot understand how the rest of the clue works.
(Other definitions for eggheads that I've seen before include "Boffins" , "Slang intellectuals with lofty domes" , "Intellectuals (colloq.)" , "Quiz programme" , "TV quiz show" .)