Consumed with rage at first, becoming calm (9)
I believe the answer is:
temperate
'calm' is the definition.
(I've seen this before)
'consumed with rage at first' is the wordplay.
'consumed with' becomes 'ate' (to eat is to consume food. I am not sure about the 'with' bit.).
'rage' becomes 'temper' (temper means anger or rage).
'at first' is a charade indicator (letters next to each other).
'ate' after 'temper' is 'TEMPERATE'.
'becoming' is the link.
Can you help me to learn more?
(Other definitions for temperate that I've seen before include "Continent" , "Showing moderation" , "Abstemious" , "with balmy climate" , "even" .)