Subtle difference (6)
I believe the answer is:
nuance
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">subtle difference</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 nuance that I've seen before include "Delicate shade of meaning" , "A hint or shade" , "Subtlety, nicety" , "Delicate shade of difference" , "Slight difference in meaning etc" .)