For each piece of wallpaper (3)
I believe the answer is:
per
'for each' is the definition.
('per' can mean for each)
'piece of wallpaper' is the wordplay.
'PER' is hidden in amongst the letters.
However, I am uncertain how this is indicated.
Can you help me to learn more?
(Other definitions for per that I've seen before include "Preposition indicating by means of" , "Preposition meaning for each" , "For each or every" , "According to" .)