Damaging time, very exciting after head quits - finally you will be involved (9)
I believe the answer is:
traumatic
'involved' is the definition.
Both the definition and answer are adjectives. Perhaps you can see a link between them that I don't see?
'damaging time very exciting after head quits finally you will be' is the wordplay.
I cannot really understand how this works, but
'time' could be 't' (abbreviation) and 't' is found within the answer.
'you' could be 'u' (commonly used in online communication) and 'u' is present in the answer.
'be' could be 'am' and 'am' is found in the leftover letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for traumatic that I've seen before include "Deeply disturbing" , "Direly shocking" , "Emotionally shocking" , "Psychologically painful" , "Psychologically damaging" .)