Dazzle briefly, possessing instant and universal allure (7)
I believe the answer is:
glamour
'universal allure' is the definition.
'glamour' can be an answer for 'allure' (thesaurus). I'm unsure of the 'universal' bit.
'dazzle briefly possessing instant' is the wordplay.
'dazzle briefly' becomes 'glaur' (I can't explain this - if you can you should believe this answer much more).
'possessing' indicates putting letters inside.
'instant' becomes 'mo'.
'glaur' enclosing 'mo' is 'GLAMOUR'.
'and' acts as a link.
(Other definitions for glamour that I've seen before include "Attractive and exciting quality" , "Groomed beauty, allure" , "Alluring beauty, very sexy" , "model's allure?" , "Alluring beauty, romantic aura" .)