The most common and most likely answer to this crossword clue is the 8 letter word MELODEON
M
E
L
O
D
E
O
N
More clues leading to the result MELODEON
- Organ song bearing fruit? On the contrary
- Men swear rival bus company lost cinema organ
- Instrument showing some lines in fruit
- Model, one playing musical instrument
- Short tune by one playing instrument
- Something juicy about composition for the organ
- Play this poem about fruit contrariwise
- This writer left poem on musical instrument
- Instrument with which this person has left theatre
- Model, one playing the organ
Buddy explains!

The straight part
We know that "old organ" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case old organ = melodeon.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 MELODEON mean?
MELODEON noun- A music hall.
- A type of reed organ with a single keyboard.
- An accordion where the melody-side keyboard is limited to the notes of diatonic scales in a small number of keys.