Long mournful complaint (8)
I believe the answer is:
jeremiad
'long mournful complaint' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for jeremiad that I've seen before include "Catalogue of complaint, woe" , "Long mournful lament about one's troubles" , "Long mournful complaint" , "tale of woe" , "Mournful complaint; list of woes" .)