Blot on the landscape (7)
I believe the answer is:
eyesore
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">blot on the landscape</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 eyesore that I've seen before include "Something ugly to look at" , "Blight" , "Horrible sight" , "pigsty" , "terrible prospect" .)