The most common and most likely answer to this crossword clue is the 10 letter word ABSORPTION
I've seen this crossword clue in Financial Times
A
B
S
O
R
P
T
I
O
N
Buddy explains!

The straight part
We know that "Occupying" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case occupying = absorption.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 ABSORPTION mean?
ABSORPTION noun- The act or process of absorbing or of being absorbed as,
- Entire engrossment or occupation of the mind.
- Mental assimilation.
- The retaining of electrical energy for a short time after it has been introduced to the dielectric.