The most common and most likely answer to this crossword clue is the 8 letter word BEMOANED
B
E
M
O
A
N
E
D
Buddy explains!

The straight part
We know that "Lamented" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lamented = bemoaned.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does BEMOANED mean?
BEMOANED verb- To moan or complain about (something).
- To be dismayed or worried about (someone), particularly because of their situation or what has happened to them.