The most common and most likely answer to this crossword clue is the 8 letter word CUSTOMER
I've seen this crossword clue in Financial Times
C
U
S
T
O
M
E
R
More clues leading to the result CUSTOMER
- He might buy copper’s big book, dear in end
- Client wants costume tailored right
- One who buys key American book by King
- Character in scrum with toe crushed
- US general keeps order – he’s never wrong
- Client’s order, in general
- More cuts baffled one paying for services
- Client requires order in general
- Right person always producing sacred word in general
- Person shopping me should be arrested by order of courts
Buddy explains!

The straight part
We know that "Client" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case client = customer.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 CUSTOMER mean?
CUSTOMER noun- A patron, a client; one who purchases or receives a product or service from a business or merchant, or intends to do so.
- A person, especially one engaging in some sort of interaction with others.