They may be locked or blown
I believe the answer is:
horns
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">they may be locked or blown</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 horns that I've seen before include "Bony outgrowths on the heads of some animals" , "Klaxons" , "Noisemakers on the road" .)