Hear pianola playing, or a wind instrument (7,4)
I believe the answer is:
aeolian harp
'a wind instrument' is the definition.
(instrument played by wind)
'hear pianola playing' is the wordplay.
'playing' indicates an anagram.
'hear'+'pianola'='hearpianola'
'hearpianola' anagrammed gives 'AEOLIAN HARP'.
'or' acts as a link.
(Other definitions for aeolian harp that I've seen before include "musical instrument" , "Wind-played instrument" , "Wind-controlled instrument" , "It's played by the wind" , "Wind-operated instrument" .)