For starters, Yoko Ono likes kippers — she also coddles some egg (4,3)
I believe the answer is:
yolk sac
'some egg' is the definition.
(I've seen this before)
'for starters yoko ono likes kippers she also coddles' is the wordplay.
'for starters' indicates taking the first letters.
The initial letters of 'yoko ono likes kippers she also coddles' is 'YOLK-SAC'.
(Other definitions for yolk sac that I've seen before include "Egg membrane" , "Provider of sustenance to an embryo" , "small food parcel" , "protection for hens due to hatch?" , "Bag containing yellow" .)