The most common and most likely answer to this crossword clue is the 5 plus 6 letter word SOUND SYSTEM
I've seen this crossword clue in The Daily Telegraph
S
O
U
N
D
S
Y
S
T
E
M
Buddy explains!
The straight part
We know that "electronic equipment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case electronic equipment = sound system.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.