Kind-hearted fan upset by punches being thrown there (6)
I believe the answer is:
caring
'kind-hearted' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for caring that I've seen before include "Kind, affectionate" , "Minding" , "Showing compassion" , "medical profession" , "Concerned, interested" .)