Emotionally shocking nervous reaction follows wound (9)
I believe the answer is:
traumatic
'emotionally shocking' is the definition.
(I've seen this before)
'nervous reaction follows wound' is the wordplay.
'nervous reaction' becomes 'tic' (I've seen this in other clues).
'follows' is a charade indicator (letters next to each other).
'wound' becomes 'trauma' (I've seen this before**).
'tic' after 'trauma' is 'TRAUMATIC'.
(Other definitions for traumatic that I've seen before include "Emotionally shocking" , "Psychologically damaging" , "Deeply disturbing" , "Psychologically painful" , "Deeply distressing" .)