The most common and most likely answer to this crossword clue is the 9 letter word FOOTFALLS
F
O
O
T
F
A
L
L
S
Buddy explains!
The straight part
We know that "Customers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case customers = footfalls.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 FOOTFALLS mean?
FOOTFALLS noun- The sound made by a footstep.
- Foot (pedestrian) traffic.