Monotonous sound (5)
(Other definitions for thrum that I've seen before include "Strum monotonously" , "Monotonously repeat" , "Tap a beat with fingers" , "Drum incessantly" , "Repetitive drone - end of weaver's thread" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">monotonous sound</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 drone that I've seen before include "Monotonous sound - member of hive" , "Talk boringly; a parasite" , "Low hum; parasite" , "Continuous sound; bee" , "Male bee for the queen" .)