The most common and most likely answer to this crossword clue is the 7 letter word RABBITS
I've seen this crossword clue in The Times
R
A
B
B
I
T
S
Buddy explains!

The straight part
We know that "Buns" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case buns = rabbits.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 RABBITS mean?
RABBITS noun- A mammal of the family Leporidae, with long ears, long hind legs and a short, fluffy tail.
- The meat from this animal.
- The fur of a rabbit typically used to imitate another animal's fur.
- A runner in a distance race whose goal is mainly to set the pace, either to tire a specific rival so that a teammate can win or to help another break a record; a pacesetter.
- A very poor batsman; selected as a bowler or wicket-keeper.
- A large element at the beginning of a list of items to be bubble sorted, and thus tending to be quickly swapped into its correct position. Compare turtle.
- Rarebit; Welsh rabbit or a similar dish: melted cheese served atop toast.