Regional dialect (6)
I believe the answer is:
patois
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">regional dialect</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 patois that I've seen before include "Dialect or jargon" , "Regional (French) dialect" , "speech" , "Dialect or non-standard language" , "Jargon or vernacular" .)