Blushing after insult mumbled indistinctly (7)
I believe the answer is:
slurred
'mumbled indistinctly' is the definition.
The answer and definition can be both to do with communicating as well as being past participle verbs.
Perhaps you can see an association between them that I can't see?
'blushing after insult' is the wordplay.
'blushing' becomes 'red' (blushing makes someone's face go red).
'after' is a charade indicator (letters next to each other).
'insult' becomes 'slur' (I've seen this in another clue).
'red' after 'slur' is 'SLURRED'.
Can you help me to learn more?
(Other definitions for slurred that I've seen before include "Uttered indistinctly" , "(Of speech) indistinctly articulated" .)