One such as I? (5-4,6)

I believe the answer is:

upper-case letter

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

'one' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'as i?' is the wordplay.
I cannot quite see how this works, but
'as' is present in the answer.
This may be the basis of the clue (or it may be nonsense).

'such' acts as a link.

Can you help me to learn more?

I've seen this clue in The Daily Express.

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.