Symbolic mathematics (7)
I believe the answer is:
algebra
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">symbolic mathematics</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 algebra that I've seen before include "Branch of generalised arithmetic" , "school subject" , "Branch of mathematics using letters and symbols" , "letters here set out the problem" , "system employing symbols" .)