The most common and most likely answer to this crossword clue is the 10 letter word PERCENTAGE
I've seen this crossword clue in The Daily Telegraph
P
E
R
C
E
N
T
A
G
E
More clues leading to the result PERCENTAGE
- For instance, at exhibition centre, salesperson returned profit
- Commission agent’s backing money to mature
- Returning agent gets a bit of money – time for share of profits?
- A proportion of leaf carrying recent damage
- Commission centre-page spread
- Salesman turns up with money! Time for a share
- Share ‘er American money with young servant outside
- Recent changes in hotel employee share
- In a bad way, PC teenager cut
- Part of centre-page spread
Buddy explains!

The straight part
We know that "Commission" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case commission = percentage.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 PERCENTAGE mean?
PERCENTAGE noun- The amount, number or rate of something, regarded as part of a total of 100; a part of a whole.
- A share of the sales, profits, gross margin or similar.
- Benefit or advantage.