The most common and most likely answer to this crossword clue is the 9 letter word DISSEMBLE
I've seen this crossword clue in The Times
D
I
S
S
E
M
B
L
E
More clues leading to the result DISSEMBLE
Buddy explains!

The straight part
We know that "Cunningly hide" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cunningly hide = dissemble.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 DISSEMBLE mean?
DISSEMBLE verb- To disguise or conceal something.
- To feign.
- To deliberately ignore something; to pretend not to notice.
- To falsely hide one's opinions or feelings.