Quite realising you can't squeeze another thing in? (5,5)

'quite realising' is the definition.
I know nothing about this answer so I can't judge whether this works.

'you can't squeeze another thing in?' is the wordplay.
I cannot quite understand how this works, but
'you' could be 'ya' (non-standard spelling as in 'see ya later') and 'ya' is present in the answer.
'another' could be 're' (I've seen this in other clues) and 're' is found within the answer.
This explanation may well be incorrect...

Can you help me to learn more?