Piece of paper on doormat (5)
I believe the answer is:
rondo
'piece' is the definition.
(type of musical composition)
'of paper on doormat' is the wordplay.
'of' indicates a hidden word.
'RONDO' is hidden within 'paper on doormat'.
(Other definitions for rondo that I've seen before include "Repetitive musical form" , "noted work" , "Music form with repeating theme" , "Musical form with returning theme" , "part of a sonata" .)