The most common and most likely answer to this crossword clue is the 6 letter word OMERTA
O
M
E
R
T
A
More clues leading to the result OMERTA
- Tradition that mum’s kept in the family?
- Thanks after measure is laid down in code of honour
- Newcomer talks, getting round code of silence
- Cheers on queen after order demanding silence
- An involuntary agitation almost reverses code of silence
- Conspiracy of silence revealed by newcomer talking
- Some clergy attack centres enforcing vow of silence …
- Mafioso custom, ultimately about upholding reserve?
- Vow of silence may even form betrothal
- Confused democrat leaves DC with vow of silence
Buddy explains!

The straight part
We know that "code of silence" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case code of silence = omerta.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 OMERTA mean?
OMERTA noun- A code of silence amongst members of a criminal organization (especially the Mafia) that forbids divulging insider secrets to law enforcement, often also followed outside of the organization in fear of retaliation; extensively, any code of silence.