A Belgian language (7)
I believe the answer is:
flemish
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a belgian language</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 flemish that I've seen before include "Belgian language" , "from the Low Countries" , "Second official language of Belgium" , "tongue" , "Of Flanders, like its language" .)