Forceful and definite (8)
I believe the answer is:
emphatic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">forceful and definite</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 emphatic that I've seen before include "In no uncertain terms" , "Forceful in expression" , "Striking" , "speaking firmly" , "Categorical" .)