The most common and most likely answer to this crossword clue is the 5 plus 2 plus 1 plus 7 letter word BIRDS OF A FEATHER
I've seen this crossword clue in The Times
B
I
R
D
S
O
F
A
F
E
A
T
H
E
R
More clues leading to the result BIRDS OF A FEATHER
- Time with dad on settee taking in English sitcom
- Similar item of furniture introduced to curious father and bride
- After stretch on couch, priest full of energy for flock
- Messy affairs bothered like-minded people
- People like each other, conducting affairs — bothered?
- “Unsafe” fiord – safe parts swimmer likes
- Bad forefathers I worked out to be group of similar type
- Likes a sitcom
- 6 likes flying
- Girl having tete-a-tete down a bit? And others like her?
Buddy explains!
The straight part
We know that "family group" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case family group = birds of a feather.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.