The most common and most likely answer to this crossword clue is the 12 letter word TRAUMATISING
I've seen this crossword clue in Financial Times
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More clues leading to the result TRAUMATISING
Buddy explains!
The straight part
We know that "Shocking" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shocking = traumatising.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 TRAUMATISING mean?
TRAUMATISING verb- To injure, e.g. tissues, by force or by thermal, chemical or other agents.
- To cause a trauma in.