The most common and most likely answer to this crossword clue is the 8 letter word FRENETIC
I've seen this crossword clue in Financial Times
F
R
E
N
E
T
I
C
More clues leading to the result FRENETIC
- De Gaulle’s language mostly about English — it turned wild
- Delirious, seeing entire chaos in football club
- Frenchman in France with much of beat that’s very busy
- Frantic if centre is moved
- Available around noon, jerk becomes mad
- Mad fellow in charge drawing in soldiers with trap
- Mad fellow, Frenchman, with nervous habit
- Agitated nervous response by loud Frenchman
- Centre, if poorly positioned, can be distracted
- Extremely agitated as foreigner starts to collapse in Crete
Buddy explains!

The straight part
We know that "very busy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case very busy = frenetic.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 FRENETIC mean?
FRENETIC noun- One who is frenetic.
- Fast, harried; having extreme enthusiasm or energy.
- Mentally deranged, insane.
- Characterised by manifestations of delirium or madness.