It may be consumed from a cup (3)
I believe the answer is:
egg
'a cup' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'it may be consumed' is the wordplay.
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'may be consumed' becomes 'gg' (I am not sure about this - if you are sure you should believe this answer much more).
'e'+'gg'='EGG'
'from' acts as a link.
Can you help me to learn more?
(Other definitions for egg that I've seen before include "Item with a yolk" , "The advertising slogan exhorted us to go to work on one" , "Hen's product" , "Reproductive cell" , "Food in a shell" .)