Gradually wear away (5)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">gradually wear away</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for erode that I've seen before include "Slowly remove" , "Abrade" , "Eat away" , "Become ground down or deteriorate" , "fragment" .)