Get to know when sure (9)

I believe the answer is:

ascertain

'get to know' is the definition.
(ascertaining is a kind of getting to know)

'when sure' is the wordplay.
'when' becomes 'as'.
'sure' becomes 'certain' ('certain' can be a synonym of 'sure').
'as'+'certain'='ASCERTAIN'

(Other definitions for ascertain that I've seen before include "Prove" , "Establish after an investigation or study" , "Confirm, make sure" , "Get to know" , "Establish, find out" .)

I've seen this clue in The Telegraph.

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.