The most common and most likely answer to this crossword clue is the 6 plus 6 letter word DIMMER SWITCH
I've seen this crossword clue in The Guardian
D
I
M
M
E
R
S
W
I
T
C
H
More clues leading to the result DIMMER SWITCH
Buddy explains!

The straight part
We know that "Electrical device" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case electrical device = dimmer switch.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.