The most common and most likely answer to this crossword clue is the 5 letter word ABUZZ
A
B
U
Z
Z
Buddy explains!
The straight part
We know that "full of activity" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case full of activity = abuzz.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 ABUZZ mean?
ABUZZ adjective- Characterized by a high level of activity or gossip; in a buzz, buzzing.