Eat away, rust (7)
I believe the answer is:
corrode
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">eat away</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">rust</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that rust can be written as corrode)</span><br/ ><br/ ></span>
(Other definitions for corrode that I've seen before include "Gradually eat away" , "Chemically weaken" , "Eg, to rust" , "Gradually weaken (metal)" , "Growth in hazel buds" .)