Be malodorous (4)
I believe the answer is:
reek
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">be malodorous</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for reek that I've seen before include "smoke in Balmoral" , "bad odour" , "Smell foully" , "Smell like 12 Across" , "hum a lot!" .)