The most common and most likely answer to this crossword clue is the 15 letter word CRIMINALISATION
I've seen this crossword clue in The Guardian
C
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More clues leading to the result CRIMINALISATION
Buddy explains!

The straight part
We know that "getting banned" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case getting banned = criminalisation.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 CRIMINALISATION mean?
CRIMINALISATION noun- The act of making a previously legal activity illegal, the act of making something a criminal offence.
- The act of turning someone into a criminal by making their activities illegal.