The most common and most likely answer to this crossword clue is the 5 letter word LEMON
I've seen this crossword clue in Independent
L
E
M
O
N
More clues leading to the result LEMON
- Fruit found in Jerusalem once
- Dud shade
- Bright yellow honeydew, perhaps partly on the turn
- Fruit gobbled up by little mongrel
- Failure of French newspaper, reactionary editor dismissed
- Revolutionary piano melodies bearing fruit
- Most of French paper’s yellow
- Yellow object that doesn’t work
- Something worthless Frenchman found in Spanish city
- An unattractive character, like Sue on her tod when upset?
Buddy explains!

The straight part
We know that "Something worthless" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case something worthless = lemon.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 LEMON mean?
LEMON noun- A yellowish citrus fruit.
- A semitropical evergreen tree, Citrus limon, that bears such fruits.
- A taste or flavour/flavor of lemons.
- A more or less bright shade of yellow associated with lemon fruits.
- A defective or inadequate item or individual.
- (shortened from “lemon flavour”) Favor.
- A piece of fanfiction involving explicit sex (named after the erotic anime series Cream Lemon).
- To flavour with lemon.
- Containing or having the flavour/flavor and/or scent of lemons.
- Of the pale yellow colour/color of lemons.
- (from "lemon tart") Smart; cheeky, vocal.