Warmed one's toes at, curled up, the day after (7)
I believe the answer is:
toasted
'warmed one's' is the definition.
The answer and definition can be both related to change as well as being past participle verbs.
Perhaps you can see a link between them that I don't see?
'toes at curled up the day after' is the wordplay.
'curled' is an anagram indicator (letters curl or twist around).
'up the day' becomes 'd' (I can't explain this - if you can you should give a lot more credence to this answer).
'after' says to put letters next to each other.
'toes'+'at'='toesat'
'toesat' with letters rearranged gives 'toaste'.
'toaste'+'d'='TOASTED'
Can you help me to learn more?
(Other definitions for toasted that I've seen before include "grilled" , "Absent Friends may be" , "Heated" , "drank to the happy couple!" , "Cooked; drank health of" .)