The most common and most likely answer to this crossword clue is the 7 letter word SHUTTER
I've seen this crossword clue in The Sunday Telegraph
S
H
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More clues leading to the result SHUTTER
- Keep mum, say, closer
- Supplier of shade and quiet, say
- Blind and quiet state
- Louvre‘s quiet, say
- Call for peace, say, that controls exposure when shooting occurs
- It’s said to eliminate noise, say, in camera component
- ‘Blind‘ is not a word to say
- Camera part that is moved to capture image of an object that is closer
- Quiet voice that provides cover
Buddy explains!

The straight part
We know that "that controls exposure when shooting occurs" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that controls exposure when shooting occurs = shutter.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 SHUTTER mean?
SHUTTER noun- One who shuts or closes something.
- (usually in the plural) Protective panels, usually wooden, placed over windows to block out the light.
- The part of a camera, normally closed, that opens for a controlled period of time to let light in when taking a picture.
- To close shutters covering.
- To close up (a building) for a prolonged period of inoccupancy.
- To cancel or terminate.