Better pack the eggs in with the vegetable (8)
I believe the answer is:
beetroot
'the vegetable' is the definition.
(beetroot is a kind of vegetable)
'better pack the eggs in' is the wordplay.
'better pack' becomes 'beetrt' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'the eggs' becomes 'oo' (two O's - O looks like an egg).
'in' means one lot of letters goes inside another.
'beetrt' going around 'oo' is 'BEETROOT'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for beetroot that I've seen before include "Vegetable cooked or used in salads and pickles" , "salad ingredient" , "Food" , "Dark red root eaten as a vegetable" , "Essential ingredient in borsch" .)