The most common and most likely answer to this crossword clue is the 6 letter word WIRING
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Buddy explains!
The straight part
We know that "circuit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case circuit = wiring.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 WIRING mean?
WIRING verb- To fasten with wire, especially with reference to wine bottles, corks, or fencing.
- To string on a wire.
- To equip with wires for use with electricity.
- To add something into an electrical system by means of wiring; to incorporate or include something.
- (usually passive) To fix or predetermine (someone's personality or behaviour) in a particular way.
- To send a message or monetary funds to another person through a telecommunications system, formerly predominantly by telegraph.
- To make someone tense or psyched up. See also adjective wired.
- To install eavesdropping equipment.
- To snare by means of a wire or wires.
- To place (a ball) so that the wire of a wicket prevents a successful shot.
- A mass of electric wires.