The most common and most likely answer to this crossword clue is the 5 letter word PIANO
I've seen this crossword clue in The Times
P
I
A
N
O
More clues leading to the result PIANO
- Nature god holding one old instrument to play
- Quiet fellow taking dip in river
- Greek character joins American returning on musical instrument
- Scotsman engaged in musical work, turning up this instrument
- Instrument originally played in area near Oxford
- Scotsman in Post Office to get instrument
- Be critical of including one old key holder
- Scotsman in post office, one of 6
- In dystopia nothing’s soft
- Greek character with a number quietly in bars
Buddy explains!

The straight part
We know that "instrument" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case instrument = piano.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 PIANO mean?
PIANO noun- A percussive keyboard musical instrument, usually ranging over seven octaves, with white and black colored keys, played by pressing these keys, causing hammers to strike strings
- Soft, quiet
- In extended use; quiet, subdued
- Softly, as a musical direction (abbreviated to p. in sheet music)