47-stringed instrument (4)
I believe the answer is:
harp
'47-stringed instrument' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for harp that I've seen before include "Traditional Gaelic musical instrument" , "Instrument (for angels?)" , "Stringed instrument" , "Large plucked instrument" , "''The ... that once through Tara's halls'' (4)" .)