Instrument from old motor in top of aeroplane (7)
I believe the answer is:
ocarina
'instrument' is the definition.
(ocarina is a kind of instrument)
'old motor in top of aeroplane' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'motor' becomes 'car' (I've seen this before).
'top of' indicates taking the first letters.
The first letter of 'aeroplane' is 'a'.
'o'+'car'+'in'+'a'='OCARINA'
'from' acts as a link.
(Other definitions for ocarina that I've seen before include "Toy-like wind instrument" , "Egg-shaped type of flute" , "toy instrument" , "Terracotta wind instrument" , "Toy flute" .)