Streetcar crossing close to you a shock (6)
I believe the answer is:
trauma
'shock' is the definition.
(thesaurus)
'streetcar crossing close to you a' is the wordplay.
'streetcar' becomes 'tram' ('tram' can be a synonym of 'streetcar').
'crossing' means one lot of letters goes inside another.
'close to' indicates one should take the final letters (the close/ending of).
The final letter of 'you' is 'u'.
'tram' enclosing '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" .)