The most common and most likely answer to this crossword clue is the 5 letter word HIVES
I've seen this crossword clue in The Daily Telegraph
H
I
V
E
S
Buddy explains!
The straight part
We know that "places buzzing with activity" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case places buzzing with activity = hives.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 HIVES mean?
HIVES noun- Itchy, swollen, red areas of the skin which can appear quickly in response to an allergen or due to other conditions.
- A structure, whether artificial or natural, for housing a swarm of honeybees.
- The bees of one hive; a swarm of bees.
- A place swarming with busy occupants; a crowd.
- A section of the registry.
- To enter or possess a hive.
- To form a hive-like entity.
- To collect into a hive.
- To store in a hive or similarly.
- To take shelter or lodgings together; to reside in a collective body.