Hear this instrument played — Aeolian harp possibly (7)
I believe the answer is:
pianola
'hear this instrument played aeolian harp possibly' is the definition.
'Pianola' can be an answer for 'instrument' (Pianola is an example). I am unsure of the rest of the definition.
'hear this instrument' is the wordplay.
I cannot really see how this works, but
'instrument' could be 'piano' (piano is a kind of instrument) and 'piano' is found in the answer.
The remaining letters 'la' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for pianola that I've seen before include "musical instrument" , "Mechanical piano" , "Melody Maker" , "Keyboard without a keyboarder!" , "Automatic instrument" .)