The most common and most likely answer to this crossword clue is the 4 plus 5 letter word MAIL ORDER
I've seen this crossword clue in The Daily Telegraph
M
A
I
L
O
R
D
E
R
More clues leading to the result MAIL ORDER
- How to sell admirer snaps — look inside
- The ‘brotherhood’ broadcast Amazon’s business
- Daily sequence used for buying from a catalogue?
- According to hearsay, chap’s degree obtained by post
- A way to purchase flexible armour by post?
- Chap reportedly given degree by post
- How crusaders acquired their protection?
- Irishman returned book purchased by post
- Type of purchase made by man reportedly having class
- Millions suffer with religious community making such a purchase
Buddy explains!

The straight part
We know that "Type of purchase" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case type of purchase = mail order.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.
Crossword Answer definitions
MAIL ORDER verb- To buy or sell goods to be delivered by mail