One making changes (8)
I believe the answer is:
reformer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">one making changes</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 reformer that I've seen before include "Luther, for one" , "One dealing with abuses" , "Luther, perhaps" , "campaigner for change" , "One who changes organisation in order to improve" .)