Thundered (7)
(Another definition for stormed that I've seen is " Charged".)
(Another definition for rumbled that I've seen is " Saw through - what the thunder did".)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thundered</span>' is the definition.<br/ ><span class="explanation-format__explanation">('boom' can be a synonym of 'thunder')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Another definition for boomed that I've seen is " Made deep resonant sound - or prospered".)