The most common and most likely answer to this crossword clue is the 6 letter word CRANNY
I've seen this crossword clue in The Daily Telegraph
C
R
A
N
N
Y
More clues leading to the result CRANNY
- Crack smuggled between Cape and New York
- Crack soldiers penetrating walls of Cretan city
- Depression? Woman in family needs new start
- Old lady gives up a lot of money for carbon fissure
- Knowing about bar’s closing and opening
- Old lady taking in clubs for good crack
- Shrewd, pinching joker’s last crack
- Caught news flash that’s going around
- Astute about right opening
- Sly circumventing rule in secret place
Buddy explains!

The straight part
We know that "crack" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case crack = cranny.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 CRANNY mean?
CRANNY noun- A small, narrow opening, fissure, crevice, or chink, as in a wall, or other substance.
- A tool for forming the necks of bottles, etc.
- To break into, or become full of, crannies.
- To haunt or enter by crannies.
- Quick; giddy; thoughtless