Greek epic about the siege of Troy (5)
I believe the answer is:
iliad
'greek epic about the siege of troy' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for iliad that I've seen before include "Homer's ancient Greek epic" , "Epic poem attributed to Homer" , "Homerian work" , "tale of woes" , "LITERATURE" .)