A shocking thing (7)
I believe the answer is:
scandal
'a shocking thing' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for scandal that I've seen before include "content of 3 [RED TOPS]?" , "Subject of Sheridan's school" , "Something shameful or disgraceful, often public" , "outrageous behaviour" , "It injures reputation" .)