Small envelope (6)
I believe the answer is:
sachet
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">small envelope</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 sachet that I've seen before include "Small bag or sealed plastic pack" , "Small packet (of, eg, shampoo)" , "Chaste as a sealed plastic bag" , "Small sealed packet" , "Small bag with sweet-smelling substance" .)