Crossword Genius

Hang on there! You're not getting a third! (4,1,6)

Ross

I believe the answer is:

just a second

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

'hang on there you're' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'not getting a third' is the wordplay.
I cannot really understand how this works, but
'not' could be 'con' (I've seen this in other clues) and 'con' is found in the answer.
'a' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in the Evening Standard.
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