Combine, blend (3)
I believe the answer is:
mix
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">combine</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(mix is a kind of combine)</span><br/ ><br/ >'<span class="explanation-format__original">blend</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that blend is a kind of mix)</span><br/ ><br/ ></span>
(Other definitions for mix that I've seen before include "Mingle, blend" , "Get on" , "= 1,009 (L.)" , "Blend or socialise" , "Blend together" .)