Paste-up (7)
I believe the answer is:
collage
'paste-up' is the definition.
(collage is a kind of paste-up)
This is all the clue.
(Other definitions for collage that I've seen before include "Stuck-on art form" , "Artwork formed from scraps of paper, photos etc" , "Paste-up" , "Art form using pieces stuck on" , "Pictures made by sticking together pieces of paper etc." .)