Boiled (7)
I believe the answer is:
seethed
'boiled' is the definition.
(seething is a kind of boiling)
This is the entire clue.
(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" .)