Plaintive poem (5)
I believe the answer is:
elegy
'plaintive poem' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for elegy that I've seen before include "Poetic lament for the dead" , "Dirge" , "A sorrowful poem like Gray's" , "Poem lamenting the dead" , "lines of regret" .)