Blackguard (3)
I believe the answer is:
cur
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">blackguard</span>' is the definition.<br/ ><span class="explanation-format__explanation">(both can mean a dishonourable person)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for cur that I've seen before include "Aggressive mongrel" , "Poor dog" , "A worthless dog or contemptible person" , "Inferior dog or one of mixed breed" , "Despicable person" .)