The most common and most likely answer to this crossword clue is the 5 letter word NIFTY
I've seen this crossword clue in The Guardian
N
I
F
T
Y
More clues leading to the result NIFTY
- Tiny feet, initially remarkably agile
- Providing temperature in New York is fine
- Rather clever, providing opening for tourism in US city
- Agile new figure, not feminine
- Smart current newspaper in US city
- Fine, independent newspaper housed in US city
- Smart leaders of new industries fire their yesmen
- Smart new 12-inch Sony at last
- Stylish and new, if totally vacuous
- Quick half-century, new opener
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 = nifty.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 NIFTY mean?
NIFTY adjective- Good, smart; useful or beneficial.
- Stylish.