Second person nursing unfilled litter (5)

I believe the answer is:

young

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

'unfilled litter' is the definition.
'young' can be an answer for 'litter' (I've seen this before). I am not sure about the 'unfilled' bit.

'second person nursing' is the wordplay.
'second person' becomes 'you' (I've seen this before).
'nursing' becomes 'ng' (I can't explain this - if you can you should believe this answer much more).
'you'+'ng'='YOUNG'

Can you help me to learn more?

(Other definitions for young that I've seen before include "Juvenile" , "Mormon leader" , "Green" , "not getting on yet" , "Inexperienced" .)

I've seen this clue in the Sydney Morning Herald.

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