The most common and most likely answer to this crossword clue is the 5 letter word MENSA
I've seen this crossword clue in The Guardian
M
E
N
S
A
More clues leading to the result MENSA
- Stars and soldiers joining army of peace
- Group for the clever chaps observed losing weight
- Chaps getting second best score at gathering of great minds
- Very clever people amend mosaic, keeping central elements
- Smart-arse types of blokes like being tossed
- Intelligent group of people endlessly miserable
- Bright bunch of blokes with a certain sort of appeal
- Group of stars or high-IQ bods? Different names
- Stars appearing down under, a bright bunch
- Manchester Evening News — it’s for clever people
Buddy explains!

The straight part
We know that "Intelligent group/Intelligent group" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case intelligent group/intelligent group = mensa.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.