The most common and most likely answer to this crossword clue is the 7 letter word RIFFLER
I've seen this crossword clue in Financial Times
R
I
F
F
L
E
R
Buddy explains!
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 RIFFLER mean?
RIFFLER noun- A mechanical device consisting of a metal box with a series of vertical slats through which material is poured and randomly divided into two samples; this process is repeated to obtain a small representative sample of a bulk material.
- A curved file used in carving wood and marble.