Summon everybody in sporting contest (4,2)

I believe the answer is:

call up

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

'summon' is the definition.
(calling up is a kind of summoning)

'everybody in sporting contest' is the wordplay.
'everybody' becomes 'all' (all people).
'in' indicates putting letters inside.
'sporting contest' becomes 'cup' (a sporting contest eg the FA Cup. I am not sure about the 'sporting' bit.).
'all' inserted into 'cup' is 'CALL-UP'.

Can you help me to learn more?

(Other definitions for call up that I've seen before include "Act of conscription into the armed forces" , "Summon; evoke" , "Ring" , "Summons for military service" , "Remember" .)

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.