Something bitter for the French, one day (5)

I believe the answer is:

lemon

I'm a little stuck... Click here to teach me more about this clue!

'something bitter' is the definition.
I can't tell whether this definition defines the answer.

'the french one day' is the wordplay.
'the french' becomes 'le' ('the' in French).
'one day' becomes 'mon' (short for Monday).
'le'+'mon'='LEMON'

'for' acts as a link.

Can you help me to learn more?

(Other definitions for lemon that I've seen before include "Something worthless" , "Leaving body" , "Strong yellow colour" , "definitely not a peach" , "Useless object" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.