Spot where we left musical instrument (6)
I believe the answer is:
zither
'musical instrument' is the definition.
(zither is a kind of musical instrument)
'spot where' is the wordplay.
'spot' becomes 'zit'.
'where' becomes 'her' (I can't justify this - if you can you should give a lot more credence to this answer).
'zit'+'her'='ZITHER'
'we left' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
(Other definitions for zither that I've seen before include "Metal-stringed soundbox" , "music player" , "Plucked musical instrument" , "Harp-like instrument" , "music producer" .)