Commercial traveller (8)
I believe the answer is:
salesman
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">commercial traveller</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 salesman that I've seen before include "Travelling rep" , "He's a seller" , "Arthur Miller wrote 'Death of a . . . . . . . .'" , "He sells strange lean mass" , "Fermented honey drink" .)