Value too highly (12)
I believe the answer is:
overestimate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">value too highly</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 overestimate that I've seen before include "give an excessive appraisal" , "Think too highly of" , "Too large a guess" , "Rate too highly" , "Value too highly" .)