The most common and most likely answer to this crossword clue is the 6 letter word REVERB
I've seen this crossword clue in The Guardian
R
E
V
E
R
B
More clues leading to the result REVERB
- Tenor’s last note upset acoustic device
- Right note upset acoustic device
- Acoustic device for ever blasting to some extent
- Acoustic effect in long note recorded backwards by Queen?
- What can change our perception forever – bacon sandwiches
- Echo note right back
- Empty bunker with continually rising echo
- Echo musical note right back
- Note resistance returns in musical device
- Echo effect always found in Rhythm & Blues
Buddy explains!

The straight part
We know that "this" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this = reverb.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 REVERB mean?
REVERB noun- (audio effects) An electronic effect which simulates echoes or reverberations in the sound signal being processed.
- To echo.
- To apply a reverb (electronic echo effect) to.