The most common and most likely answer to this crossword clue is the 7 letter word F-STOPS
I've seen this crossword clue in Financial Times
F
-
S
T
O
P
S
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 F-STOPS mean?
F-STOPS noun- Any of the discrete steps or stopping points for adjusting the aperture of a lens, either marked on a ring on the lens and adjusted by rotating that ring or marked in the display of a digital camera and adjusted by buttons or touch-sensitive controls.