Most impolite (6)
I believe the answer is:
rudest
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">most impolite</span>' is the definition.<br/ ><span class="explanation-format__explanation">('rude' can be similar in meaning to 'impolite')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for rudest that I've seen before include "Most bad mannered!" , "Most vulgar" , "Most unrefined" , "Least polite, most unmannerly" , "Most ill-mannered" .)