Collaborating (2,6)
I believe the answer is:
in league
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">collaborating</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for in league that I've seen before include "United" , "Co-operating" , "as teams usually are" , "belonging to a competitive group of teams" , "Collaborating" .)