Bellow, roar (7)
I believe the answer is:
thunder
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">bellow</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">roar</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thundering is a kind of roaring)</span><br/ ><br/ ></span>
(Other definitions for thunder that I've seen before include "Red hunt for a loud noise" , "Heavenly rumbling" , "Loud rumbling noise" , "Noise heard after lightning" , "Noise named after the god Thor" .)