The most common and most likely answer to this crossword clue is the 7 letter word TRAFFIC
I've seen this crossword clue in Financial Times
T
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More clues leading to the result TRAFFIC
Buddy explains!
The straight part
We know that "Dishonest trading/vehicles" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dishonest trading/vehicles = traffic.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 TRAFFIC mean?
TRAFFIC noun- Pedestrians or vehicles on roads, or the flux or passage thereof.
- Commercial transportation or exchange of goods, or the movement of passengers or people.
- Illegal trade or exchange of goods, often drugs.
- Exchange or flux of information, messages or data, as in a computer or telephone network.
- Commodities of the market.
- To pass goods and commodities from one person to another for an equivalent in goods or money; to buy or sell goods
- To trade meanly or mercenarily; to bargain.
- To exchange in traffic; to effect by a bargain or for a consideration.