Gilbert and Sullivan opera (3,6)
(Other definitions for the mikado that I've seen before include "musical entertainment" , "What may be on at the Savoy" , "G & S operetta" , "Operetta set in Japan" , "Staged work" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">gilbert and sullivan opera</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 iolanthe that I've seen before include "G&S twenty three down" , "Staged work" , "G & S' alternative for "The Peer and the Peri"" , "one of 63 [OPERETTAS]" , "The Peer and the Peri is its alternative title" .)