Streetcar crossing close to you a shock (6)
I believe the answer is:
trauma
'shock' is the definition.
(I've seen this before)
'streetcar crossing close to you a' is the wordplay.
'streetcar' becomes 'tram' (synonyms).
'crossing' is an insertion indicator (to cross can mean to go over or around).
'close to' says to take the final letters (the 'close' to the word).
The last letter of 'you' is 'u'.
'tram' going around 'u' is 'traum'.
'traum'+'a'='TRAUMA'
(Other definitions for trauma that I've seen before include "Nervous shock" , "Emotional shock producing lasting effect" , "Psychological wound" , "Shock with long-lasting effects" , "Emotional shock, long-lasting" .)