The most common and most likely answer to this crossword clue is the 5 letter word SEPTS
I've seen this crossword clue in The Times
S
E
P
T
S
More clues leading to the result SEPTS
Buddy explains!
The straight part
We know that "Groups" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case groups = septs.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 SEPTS mean?
SEPTS noun- A clan, tribe, or family, proceeding from a common progenitor (used especially of the ancient clans in Ireland).
- An enclosure; a railing.