The most common and most likely answer to this crossword clue is the 6 letter word BRIDES
I've seen this crossword clue in The Daily Telegraph
B
R
I
D
E
S
More clues leading to the result BRIDES
Buddy explains!

The straight part
We know that "They were banned" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they were banned = brides.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 BRIDES mean?
BRIDES noun- A woman in the context of her own wedding; one who is going to marry or has just been married.
- An object ardently loved.
- To make a bride of
- An individual loop or other device connecting the patterns in lacework