Of the olfactory organ (5)
I believe the answer is:
nasal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">of the olfactory organ</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know this)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nasal that I've seen before include "Like a twang" , "Of sound, as if it came through the nose" , "Like some spray" , "nozzle" , "old face-saver" .)