One who vacillates (7)
I believe the answer is:
waverer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">one who vacillates</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 waverer that I've seen before include "Shilly-shallier" , "Irresolute person" , "One who can't make up his mind" , "One who is irresolute" , "One who vacillates" .)