Commercial activity (8)
I believe the answer is:
business
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">commercial activity</span>' is the definition.<br/ ><span class="explanation-format__explanation">(business is a kind of commercial activity)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for business that I've seen before include "Trade - one's concerns or affairs" , "Company U occupation" , "Work - shop" , "complicated problem" , "outfit" .)