Panic mostly produces evidence of trauma (4)
I believe the answer is:
scar
'evidence of trauma' is the definition.
'scar' can be an answer for 'trauma'. I'm not certain of the 'evidence of' bit.
'panic mostly' is the wordplay.
'panic' becomes 'scare' (synonyms).
'mostly' means to remove the last letter (most but not all of the word).
'scare' with its last letter removed is 'SCAR'.
'produces' is the link.
Can you help me to learn more?
(Other definitions for scar that I've seen before include "Leave wound mark" , "It shows where wound was" , "Effect of unpleasant experience" , "Mark left by old wound" , "Steep rock - blemish" .)