Eat quantity in hard fruit (7)
I believe the answer is:
consume
'eat' is the definition.
(I know that consume is a type of eat up)
'quantity in hard fruit' is the wordplay.
'quantity' becomes 'sum' (sum is a kind of quantity).
'in' is an insertion indicator.
'hard fruit' becomes 'cone' (I can't justify this - if you can you should believe this answer much more).
'sum' going into 'cone' is 'CONSUME'.
Can you help me to learn more?
(Other definitions for consume that I've seen before include "Use up" , "Eat, drink" , "Devour" , "Exhaust" .)