Meteorological boundary (5)
I believe the answer is:
front
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">meteorological boundary</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for front that I've seen before include "Impudence" , "confident manner?" , "Boldness of manner" , "Forward part - weather feature" , "Forepart - audacity" .)