The most common and most likely answer to this crossword clue is the 9 letter word PURCHASER
I've seen this crossword clue in Financial Times
P
U
R
C
H
A
S
E
R
More clues leading to the result PURCHASER
- Cleaner drinks tea with second customer
- Chief steward brought round tea for customer
- He buys nearly neat vodka after a beer
- Patron has ship’s officer storing tea
- Person buying drink welcomed by ship’s finance officer
- Buyer of tea’s in cleaner surroundings
- One buying almost flawless jumper
- Tea break for cashier and buyer
- Person who buys almost perfect hunter
- One buys almost neat second drink
Buddy explains!

The straight part
We know that "Patron" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case patron = purchaser.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 PURCHASER mean?
PURCHASER noun- One who purchases.