The most common and most likely answer to this crossword clue is the 5 letter word CANNY
I've seen this crossword clue in Independent
C
A
N
N
Y
More clues leading to the result CANNY
Buddy explains!

The straight part
We know that "Clever" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case clever = canny.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 CANNY mean?
CANNY adjective- Careful, prudent, cautious.
- Knowing, shrewd, astute.
- Frugal, thrifty.
- Pleasant, fair, favorable or agreeable to deal with.
- Gentle, quiet, steady.
- Very, considerably; quite, rather.
- Gently, quietly; carefully, skilfully.
- (especially of sound) Sounding as if it is coming through a tin can.