Most of a meringue could, say, start to go pale (3,5)
I believe the answer is:
'most of a meringue' is the definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'say start to go pale' is the wordplay.
'say' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'start to' says to take the initial letters.
'pale' becomes 'white' (pale in colour).
The initial letter of 'go' is 'g'.
'could' acts as a link.
Can you help me to learn more?
(Other definitions for egg white that I've seen before include "Meringue ingredient" , "Albumen, not the yolk" , "Cake ingredient" , "Albumen, transparent ovum content" .)