First to treat hothead mugged - it resonated (8)
I believe the answer is:
throbbed
'first to treat hothead mugged it resonated' is the definition.
I can't judge whether this definition defines the answer.
'first to treat hothead mugged' is the wordplay.
'first to' indicates taking the first letters.
'mugged' becomes 'robbed' (I can't explain this - if you can you should give a lot more credence to this answer).
The initial letters of 'treat hothead' is 'th'.
'th'+'robbed'='THROBBED'
Can you help me to learn more?
(Other definitions for throbbed that I've seen before include "Pulsated" , "Pulsed with noise, pain" .)