Wallpaper adhesive (5)
I believe the answer is:
paste
'wallpaper adhesive' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for paste that I've seen before include "Food for spreading or fixative" , "Adhesive - thrash" , "Tapes (anag.)" , "(In computing) insert text into a document" , "Wallpaper glue" .)