Rank-smelling (5)
I believe the answer is:
fetid
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">rank</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">smelling</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for fetid that I've seen before include "Having a stale and unpleasant smell" , "Smelling bad, stinking" , "Stinking, like animal breath" , "Smelly through decay" , "Putrid and stinking" .)