Champion, as a cause (7)
I believe the answer is:
espouse
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">champion as a cause</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for espouse that I've seen before include "Marry -- take on as a cause" , "help!" , "Adopt - give support to" , "Follow and promote a cause" , "See opus (anag)" .)