The most common and most likely answer to this crossword clue is the 10 letter word MERCANTILE
I've seen this crossword clue in Financial Times
M
E
R
C
A
N
T
I
L
E
More clues leading to the result MERCANTILE
- Like trade involving churchgoer in shabby headgear
- Commercial cleaner – last bit of scum it removed
- Americans who rocked up have roofing skills like tradespeople
- Recent mail shot in connection with trade
- Trading in claret, drunk behind setter
- Commercial mail centre destroyed
- Mail centre becomes profit oriented
- Commercial centre with mail being sent out
- Tees upset about hypocrisy concerning trade
- Yours truly playing clarinet in commercial
Buddy explains!

The straight part
We know that "Trading" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case trading = mercantile.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 MERCANTILE mean?
MERCANTILE adjective- Concerned with the exchange of goods for profit.
- Of or relating to mercantilism.