Thoreau's mentor (7)

I believe the answer is:
emerson
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thoreau's mentor</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for emerson that I've seen before include "Ralph Waldo ......., 19th century American transcendentalist" , "Ralph Waldo --, US poet" , "Ralph Waldo . . . . . . ., wrote The American Scholar" , "Ralph Waldo --, US author" , "American author, 1803-82" .)