Long poem (4)
I believe the answer is:
epic
'long poem' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for epic that I've seen before include "(Of) immense (proportions)" , "Long poem telling of great events" , "Colossal" , "Heroic, huge" , "long poem telling of heroic deeds" .)