"___, Oh ___" (Thomas Moore poem)

ERIN

Think of the poetic nickname for Ireland that starts with "E" and fits this lament.

This clue references the famous 19th-century poem "Erin, Oh Erin" by Irish poet Thomas Moore, where "Erin" is a poetic name for Ireland. The blank spaces hint at a repeated word, and the answer fits both the rhythm of the title and its cultural meaning. Since the poem is well-known in Irish literature, solvers familiar with it or Irish nicknames would recognize "Erin" right away. The comma in the clue also signals the answer is a single word repeated.