Devour entirety inside ice cream container (7)
I believe the answer is:
consume
'devour' is the definition.
(I know that devour can be written as consume)
'entirety inside ice cream container' is the wordplay.
'entirety' becomes 'sum' (I've seen this in another clue).
'inside' means one lot of letters goes inside another.
'ice cream container' becomes 'cone' (I've seen this in another clue).
'sum' going inside 'cone' is 'CONSUME'.
(Other definitions for consume that I've seen before include "Exhaust" , "Use up" , "Devour" , "Eat, drink" .)