The most common and most likely answer to this crossword clue is the 7 letter word FLOGGER
I've seen this crossword clue in The Times
F
L
O
G
G
E
R
More clues leading to the result FLOGGER
Buddy explains!

The straight part
We know that "salesman" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case salesman = flogger.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 FLOGGER mean?
FLOGGER noun- One who flogs.
- (BDSM) A lightweight whip with multiple lashes.