International language (9)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">international language</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for esperanto that I've seen before include "Artificial language invented for international use" , "Ape tenors (anag.)" , "largely unknown language" , "common language" , "Artificial speech-form" .)