The most common and most likely answer to this crossword clue is the 7 letter word ENCRYPT
I've seen this crossword clue in The Daily Telegraph
E
N
C
R
Y
P
T
More clues leading to the result ENCRYPT
- Scramble and vault on walls of Eton
- Ultimately hide in cellar in disguise
- Awful pity CERN has no one to encode data
- Starts to engage underground cell to put messages into code
- Scramble record containing name and call time
- Letter to lament exercising disguise for security
- Unprotected gent in front of vault put in code
- French in underground facility take action to restrict access
- Provide security to corners of graveyard
- Shout top principal is in hospital department and scramble
Buddy explains!

The straight part
We know that "put in code" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case put in code = encrypt.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 ENCRYPT mean?
ENCRYPT verb- To conceal information by means of a code or cipher.