Drop behind (5)
I believe the answer is:
trail
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">drop behind</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for trail that I've seen before include "Scent or track followed in hunting" , "Spoor - lag behind" , "Forest path" , "Need to catch up with" , "Stalk" .)