Beginning two terms of tennis (6)

I believe the answer is:

outset

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

'beginning' is the definition.
(I know that beginning can be written as outset)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for outset that I've seen before include "Set out in the beginning" , "Kickoff time?" , "origin" , "Starting point" , "Opening stage" .)

I've seen this clue in The Times.

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.