The most common and most likely answer to this crossword clue is the 12 letter word GLOCKENSPIEL
I've seen this crossword clue in Financial Times
G
L
O
C
K
E
N
S
P
I
E
L
More clues leading to the result GLOCKENSPIEL
- Peg once adjusted with skill in instrument
- Instrument identified in general speech outside bar?
- Instrument from single EP playing outside bar
- Music-maker’s sleeping rough, eating jam
- Sleeping rough holding rugby forward and instrument
- Skip college, excited to get hold of new instrument
- Music producer secure in sleeping around?
- Music player, sleeping rough, covered hair
- Music producer secure in sleeping around
- Epic song Kelly plays after throwing out unknown instrument
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 = glockenspiel.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 GLOCKENSPIEL mean?
GLOCKENSPIEL noun- A musical instrument of the percussion idiophone family of instruments; like the xylophone, it has tuned bars arranged like the keys on a piano, and is also smaller in size and higher in pitch.