National song (6)
I believe the answer is:
anthem
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">national song</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 anthem that I've seen before include "National melody" , "National tune" , "Song in praise of a nation" , "The man for a rousing song" , "air of patriotism?" .)