See the duke simmered (7)
I believe the answer is:
seethed
'simmered' is the definition.
The definition and answer can be both related to change as well as being past participle verbs.
Maybe they are linked in a way I don't understand?
'see the duke' is the wordplay.
'duke' becomes 'd' (abbreviation).
'see'+'the'+'d'='SEETHED'
Can you help me to learn more?
(Other definitions for seethed that I've seen before include "Was furious" , "Boiled, with anger perhaps" , "Was very cross" , "was fuming" , "Boiled; was intensely angry" .)