Mournful poem (5)
I believe the answer is:
elegy
'mournful poem' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for elegy that I've seen before include "Poem penned beside church" , "Sad or reflective poem" , "Poem for the departed" , "Poem as Gray's in churchyard" , "A sorrowful poem - Gray wrote a famous one" .)