The most common and most likely answer to this crossword clue is the 4 letter word FLEA
I've seen this crossword clue in The Times
F
L
E
A
More clues leading to the result FLEA
- Female star shortened jumper
- When talking, take off jumper
- Jacob’s wife spends hour going after fine jumper
- Circus performer is to escape during broadcast
- A mischievous thing coming up that may irritate?
- Tiny creature chewed leaf
- Tiny creature initially frisking over meadow
- Sort of market for jumper
- Insect up sticks caught
- Worn-out fan belt bodged together with tie
Buddy explains!

The straight part
We know that "Worn-out" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case worn-out = flea.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 FLEA mean?
FLEA noun- A small, wingless, parasitic insect of the order Siphonaptera, renowned for its bloodsucking habits and jumping abilities.
- A thing of no significance.
- To remove fleas from (an animal).
- To cause to fly; put to flight; drive off (by frightening).
- To frighten; scare; terrify.
- To be fear-stricken.