Combination of porridge and egg that will go off (4,4)
I believe the answer is:
time bomb
'egg that will go off' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'combination of porridge' is the wordplay.
I cannot quite understand how this works, but
'of' could be 'o' and 'o' is found in the answer.
'porridge' could be 'time' (porridge is slang for time in prison) and 'time' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'and' is the link.
Can you help me to learn more?
(Other definitions for time bomb that I've seen before include "Delayed explosive" , "Preset explosive device" , "Detonating mechanism with clock" , "one should go off to order" , "Preprogrammed explosive" .)