Cereal, etc, going off with pressure inside container (10)
I believe the answer is:
receptacle
'container' is the definition.
(I know that container can be written as receptacle)
'cereal etc going off with pressure' is the wordplay.
'going off with' indicates an anagram.
'pressure' becomes 'p' (abbreviation).
'cereal'+'etc'='cerealetc'
'cerealetc' with its letters mixed up with 'p' can make 'RECEPTACLE'.
'inside' is the link.
(Other definitions for receptacle that I've seen before include "What may contain something" , "Object made to contain something" , "bin, perhaps" , "Container" , "Holder" .)