Some relief from the rants of Mad John Bull? (10)

'rants of mad john bull?' is the definition.
Although both the answer and definition are plural nouns, I cannot understand how one could define the other.

'some relief from the' is the wordplay.
I cannot quite see how this works, but
'some' could be 'a' and 'a' is present in the answer.
'from' could be 'in' (I've seen this in other clues) and 'in' is found within the answer.
This explanation may well be incorrect...

Can you help me to learn more?