Division of a long poem (5)
I believe the answer is:
canto
'division of a long poem' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for canto that I've seen before include "Each of sections into which long poem is divided" , "piece of poetry" , "part of long poem" , "Poetic piece" , "Musical part" .)