Leave small portion around to dine on (4,2)
I believe the answer is:
beat it
'leave small' is the definition.
'beat it' can be an answer for 'leave' (I've seen this before). I am not sure about the 'small' bit.
'portion around to dine on' is the wordplay.
'portion' becomes 'ti' (ti is a kind of portion).
'around' shows that the letters should be reversed in order.
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'dine on' becomes 'beat' (I can't explain this - if you can you should give a lot more credence to this answer).
'ti' backwards is 'it'.
'it' put after 'beat' is 'BEAT IT'.
Can you help me to learn more?
(Other definitions for beat it that I've seen before include "Slang order to go away, get lost" , "leave" , "Clear off!" , "Scram, take a powder" , "Scarper" .)