Of the poorest quality (5)
I believe the answer is:
worst
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">of the poorest quality</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for worst that I've seen before include "Most severe" , "Far from the best - defeat" , "Least competent" , "Direst" , "Make mincemeat of" .)