Designate superior emirate (5)

I believe the answer is:

dubai

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

'emirate' is the definition.
(Dubai is an emirate of the UAE)

'designate superior' is the wordplay.
'designate' becomes 'dub' (I've seen this in another clue).
'superior' becomes 'ai' (I can't justify this - if you can you should believe this answer much more).
'dub'+'ai'='DUBAI'

Can you help me to learn more?

(Other definitions for dubai that I've seen before include "Middle Eastern destination" , "capital and port" , "Gulf city/state" , "Gulf emirate and port city" , "Country" .)

I've seen this clue in the Sydney Morning Herald.

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.