Postal wrapper (8)
I believe the answer is:
envelope
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">postal wrapper</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for envelope that I've seen before include "Sheath, wrapping" , "something to push?" , "what's to be posted in here?" , "Container for letter" , "Rectangular paper container" .)