Organisation that’s leading in tennis? (3-2)
I believe the answer is:
set-up
'organisation' is the definition.
(I've seen this before)
'leading in tennis?' is the wordplay.
I cannot really understand how this works, but
'leading' could be 'up' (up can mean winning a sports match) and 'up' is present in the answer.
The remaining letters 'set' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for set-up that I've seen before include "organisation" , "in which one is made victim" , "Arrangement" , "Organization" .)