The beginning, but not the first round! (6,3)
I believe the answer is:
square one
'the beginning but not' is the definition.
I can't tell whether this defines the answer.
'first round' is the wordplay.
I cannot really see how this works, but
'first' could be 'one' (I've seen this in another clue) and 'one' is found in the answer.
The remaining letters 'square' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'the' acts as a link.
Can you help me to learn more?
(Other definitions for square one that I've seen before include "back here after failure" , "Back to . . . . . . . . . - at starting point with no progress made" .)