The most common and most likely answer to this crossword clue is the 7 letter word WHEEZES
I've seen this crossword clue in The Guardian
W
H
E
E
Z
E
S
Buddy explains!

The straight part
We know that "Cunning plans" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cunning plans = wheezes.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 WHEEZES mean?
WHEEZES noun- A piping or whistling sound caused by difficult respiration.
- An ordinary whisper exaggerated so as to produce the hoarse sound known as the "stage whisper"; a forcible whisper with some admixture of tone.
- (British, Irish) An ulterior scheme or plan
- Something very humorous or laughable.
- To breathe hard, and with an audible piping or whistling sound, as persons affected with asthma.