Boiled (7)
I believe the answer is:
seethed
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">boiled</span>' is the definition.<br/ ><span class="explanation-format__explanation">('seethe' can be a synonym of 'boil')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for seethed that I've seen before include "Boiled; was intensely angry" , "Was very cross" , "Was furious" , "Boiled, with anger perhaps" , "was fuming" .)