The most common and most likely answer to this crossword clue is the 6 letter word CARNEY
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Buddy explains!

The straight part
We know that "Cunning" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cunning = carney.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 CARNEY mean?
CARNEY noun- A person who works in a carnival (often one who uses exaggerated showmanship or fraud).
- The jargon used by carnival workers.
- A carnival.
- Flattery.
- To cajole, wheedle, or coax.