The most common and most likely answer to this crossword clue is the 7 letter word CONCEAL
I've seen this crossword clue in Financial Times
C
O
N
C
E
A
L
More clues leading to the result CONCEAL
- Hide in attic, once alone
- Person inside ruffled lace mask
- Hide as soon as having entered western state
- Hide criminal Alec deviously
- Hide a line put under chapter previously
- Shelter, formerly in a state
- Keep out of sight to study sound of sea creature
- Previously in California to hide
- Study what sounds like marine mammal’s hide
- Hide at one time found in California
Buddy explains!

The straight part
We know that "Hide" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hide = conceal.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 CONCEAL mean?
CONCEAL verb- To hide something from view or from public knowledge, to try to keep something secret.