Empty odes? Wrong to include a legendary Irish poet (6)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

O [de] S (empty = inner letters removed) + SIN (wrong, as a noun = a bad deed), including A . Supposed author of a cycle of poems published by the 18th-century Scottish poet James Macpherson; it’s been suggested that Macpherson wrote much of it himself, based on earlier traditional poems.