Customs officer's concern (9)
I believe the answer is:
smuggling
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">customs officer's concern</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 smuggling that I've seen before include "Importing illegally" , "Running contraband" , "Occupation of runner" .)