Four-line stanza (8)
I believe the answer is:
quatrain
'four-line stanza' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for quatrain that I've seen before include "Stanza or poem of four lines" , "Poetry" , "Type of verse with four lines" , "Four-line stanza" , "Four-lined verse" .)