The most common and most likely answer to this crossword clue is the 5 letter word TRASH
I've seen this crossword clue in The Daily Telegraph
T
R
A
S
H
More clues leading to the result TRASH
- Scraps expert conclusion? Unwise
- Trudge as leader of tour over unsightly spots
- Waste time being over-hasty
- Tory leader spots scum
- Condemn revolutionary painting? Be quiet
- Refuse to abandon first husband in crush
- Section of orchestra should refuse
- Refuse to start treating skin problem
- Runt finally spots litter
- Run into walrus, maybe causing wreck
Buddy explains!

The straight part
We know that "litter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case litter = trash.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 TRASH mean?
TRASH noun- Useless things to be discarded; rubbish; refuse.
- A container into which things are discarded.
- Something worthless or of poor quality.
- People of low social status or class. (See, for example, white trash or Eurotrash.)
- A fan who is excessively obsessed with their fandom and its fanworks.
- Temporary storage on disk for files that the user has deleted, allowing them to be recovered if necessary.
- A collar, leash, or halter used to restrain a dog in pursuing game.
- To discard.
- To make into a mess.
- To beat soundly in a game.
- To disrespect someone or something
- To free from trash, or worthless matter; hence, to lop; to crop.
- To treat as trash, or worthless matter; hence, to spurn, humiliate, or crush.
- To hold back by a trash or leash, as a dog in pursuing game; hence, to retard, encumber, or restrain; to clog; to hinder vexatiously.