Practices, as a trade (5)
I believe the answer is:
plies
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">practices as a trade</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for plies that I've seen before include "Works steadily (at trade)" , "Works steadily -- ballet steps" .)