Undesirable people (4-4)
(Other definitions for riff-raff that I've seen before include "rubbish" , "Disreputable people" , "Rabble" , "Hoi polloi" , "Dregs of society" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">undesirable people</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for riffraff that I've seen before include "Crowd regarded with disdain" , "Dregs of society" , "Rubbish" , "Rabble, crowd of unruly people" , "Disreputable people, rabble" .)