Half of 2 and 3 done (4)
I believe the answer is:
past
'done' is the definition.
(both can mean finished)
'half of 2 and 3' is the wordplay.
'half of' suggests halving the letters.
't' becomes 'pair' (pair is a kind of t).
'and' says to put letters next to each other.
'3' becomes 'st' (I can't explain this - if you can you should give a lot more credence to this answer).
'pair' cut in half is 'pa'.
'pa'+'st'='PAST'
Can you help me to learn more?
(Other definitions for past that I've seen before include "Bygone" , "Days gone by" , "Beyond" , "tense" , "Ended" .)