Crossword Genius

Made-up address politician chasing promotion might give? (2,3)

Ross

I believe the answer is:

ad lib

'made-up address' is the definition.
(an improvised utterance or address)

I cannot understand how the rest of the clue works.

(Other definitions for ad lib that I've seen before include "As You Like It?" , "Perform without a script" , "Speak unprepared" , "Freely available" , "Made-up" .)

I've seen this clue in The Guardian.
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.