Chilling mostly after injury — that's good to hear (8)
I believe the answer is:
harmonic
'good to hear' is the definition.
I can't judge whether this definition defines the answer.
'chilling mostly after injury' is the wordplay.
'chilling' becomes 'icy' (I've seen this in another clue).
'mostly' means to remove the last letter (most but not all of the word).
'after' is a charade indicator (letters next to each other).
'injury' becomes 'harmon' (I am not sure about this - if you are sure you should believe this answer much more).
'icy' with its last letter taken away is 'ic'.
'ic' after 'harmon' is 'HARMONIC'.
'that's' is the link.
Can you help me to learn more?
(Other definitions for harmonic that I've seen before include "Related note - type of progression" , "Musical" , "I march on (anag)" , "Relating to pleasing note combinations" , "Tone" .)