The most common and most likely answer to this crossword clue is the 6 letter word TRAUMA
I've seen this crossword clue in Financial Times
T
R
A
U
M
A
More clues leading to the result TRAUMA
- Union leader in public vehicle getting over a shock
- Streetcar crossing close to you: a shock
- Emotional shock when former president nearly accepts answer
- President's cut, receiving a wound
- Shock a maiden with essentially adult paintings from the East
- Unionist stifled by a market in retreat gets deep shock
- Streetcar crossing close to you a shock
- Shock as naked guy boards vehicle close to arena
- Shock term oddly imposed on a university degree
- Vehicle rounds bend before a shock
Buddy explains!

The straight part
We know that "shock" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shock = trauma.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does TRAUMA mean?
TRAUMA noun- Any serious injury to the body, often resulting from violence or an accident.
- An emotional wound leading to psychological injury.
- An event that causes great distress.