Begin to make an acquaintance (9)
I believe the answer is:
introduce
'begin' is the definition.
(I know that introduce is a type of begin)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for introduce that I've seen before include "Propose" , "To add" , "Bring into practice - reduction (anag)" , "Make one person known to another" , "Bring in something or someone new" .)