Talk too much of careless carnage (3)
I believe the answer is:
nag
'talk too much' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'of careless carnage' is the wordplay.
'of' says the answer is hidden in the clue.
'NAG' is hidden within 'careless carnage'.
Can you help me to learn more?
(Other definitions for nag that I've seen before include "Mount" , "(Of pain) ache dully; horse (colloq.)" , "Find fault" , "Harry" , "Annoy the old horse persistently" .)