Legendary Irish bard (6)
I believe the answer is:
ossian
'legendary irish bard' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ossian that I've seen before include "Legendary Gaelic poet faked by Macpherson" , "Gaelic bard, son of Fingal" , "Legendary Cthree Gaelic bard" , "Fictitious Irish poet" , "Invented Irish hero" .)