Boy servant (4)
I believe the answer is:
page
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">boy servant</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 page that I've seen before include "Leaf - young attendant" , "a significant bit of history?" , "Boy at match" , "Leaf; call over PA system" , "Young male attendant" .)