Of characters, a villainous one in the past (4)

I believe the answer is:

iago

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

'of characters a villainous' is the definition.
I can't judge whether this definition defines the answer.

'one in the past' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in the past' becomes 'ago' ('ago' can be a synonym of 'in the past').
'i'+'ago'='IAGO'

Can you help me to learn more?

(Other definitions for iago that I've seen before include "stage villain" , "Othello's enemy" , "Advisor to soldier" , "Shakespeare's jealous villain" , "Othello's treacherous officer" .)

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.