Stationery item (6)
(Other definitions for envelope that I've seen before include "what's to be posted in here?" , "Container for papers" , "Wrapper for 31ac" , "Postal wrapper" , "skin?" .)
(Other definitions for paper clip that I've seen before include "staple alternative?" , "it collects leaves together" , "I can hold things together" , "Small piece of office equipment" , "Fastener for documents etc" .)
'stationery item' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for rubber that I've seen before include "Elastic material" , "Stationery item" , "Elastic substance; set of bridge games" , "Elastic substance - unit of play (at bridge)" , "a bit of bridge" .)
(Other definitions for treasury tag that I've seen before include "One holds papers" , "paper holder" , "Short cord with metal ends, for holding papers together" .)