The most common and most likely answer to this crossword clue is the 6 plus 2 plus 5 letter word VOLUME OF TRADE
I've seen this crossword clue in Financial Times
V
O
L
U
M
E
O
F
T
R
A
D
E
Buddy explains!
The straight part
We know that "What sales staff record/a ledger" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what sales staff record/a ledger = volume of trade.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.