From the buffet, getting through a portion of chicken and fish (7)
I believe the answer is:
whiting
'fish' is the definition.
(whiting is a kind of fish)
'from the buffet getting through' is the wordplay.
'from' becomes 'wing' (I can't explain this - if you can you should give a lot more credence to this answer).
'the buffet' becomes 'hit' (buffet can mean to beat or pound).
'getting through' means one lot of letters goes inside another.
'wing' enclosing 'hit' is 'WHITING'.
'a portion of chicken and' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for whiting that I've seen before include "Small sea fish or ground chalk for painting" , "[SOMETHING FISHY]" , "Edible marine fish" , "Small fish related to cod" , "North Atlantic food fish" .)