The most common and most likely answer to this crossword clue is the 7 letter word CUT-OUT
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Buddy explains!
The straight part
We know that "safety device" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case safety device = cut-out.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 CUT-OUT mean?
CUT-OUT noun- A hole or space produced when something is removed by cutting.
- A piece cut out of something.
- A trusted middleman or intermediary, especially in espionage.
- Clip art.
- Any of several devices that halts the flow of a current, especially an electric current; a trip-switch or trip.
- A switch that changes the current from one circuit to another, or for shortening a circuit.
- A railway cutting.
- The separation of a group of cattle from a herd; the place where they are collected.