Auction site (4)
I believe the answer is:
ebay
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">auction site</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ebay that I've seen before include "Internet sales facility" , "Online selling site" , "Online market" , "Modern marketplace" , "Electronic marketplace" .)