The most common and most likely answer to this crossword clue is the 5 letter word VENAL
I've seen this crossword clue in The Guardian
V
E
N
A
L
Buddy explains!

The straight part
We know that "Dishonest" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dishonest = venal.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 VENAL mean?
VENAL adjective- Venous; pertaining to veins.
- For sale; available for purchase.
- Of a position, privilege etc.: available for purchase rather than assigned on merit.
- Capable of being bought (of a person); willing to take bribes.
- (of behaviour etc.) Corrupt, mercenary.