The most common and most likely answer to this crossword clue is the 7 letter word CHANGER
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More clues leading to the result CHANGER
Buddy explains!
The straight part
We know that "switching device" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case switching device = changer.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 CHANGER mean?
CHANGER noun- Someone or something who changes things.
- Someone or something that changes or transforms itself.
- A person employed in changing or discounting money.