Part of a poem (6)
I believe the answer is:
stanza
'part of a poem' is the definition.
('stanza' is part of 'poem')
This is all the clue.
(Other definitions for stanza that I've seen before include "Unit of a poem" , "Fixed number of lines of verse" , "piece by poet" , "Lines forming a unit of verse" , "Verse of poem" .)