Union paper ripped up? (8)
I believe the answer is:
confetti
'union paper' is the definition.
'confetti' can be an answer for 'paper' (confetti is a kind of paper). I am not sure about the 'union' bit.
I don't understand how the rest of the clue works.
(Other definitions for confetti that I've seen before include "cast only for union celebration" , "To infect (anag)" , "Celebratory scraps of coloured paper thrown at weddings" , "Throw it at the wedding, it's in bits" , "Paper used at weddings" .)