Irish national symbol (4)
I believe the answer is:
harp
'irish national symbol' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for harp that I've seen before include "Stick to one theme" , "Stringed instrument" , "Heavenly instrument?" , "Talk tiresomely using upright musical instrument" , "Lyre" .)