Most frank (8)
I believe the answer is:
bluntest
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">most frank</span>' is the definition.<br/ ><span class="explanation-format__explanation">('blunt' can be a synonym of 'frank')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for bluntest that I've seen before include "Most brutally honest" , "most plain-spoken" , "Least sharp" .)