Pious posse on the rampage? You're probably right (1,7,2)
I believe the answer is:
i suppose so
'you're probably right' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'pious posse on the rampage?' is the wordplay.
'on the rampage?' indicates anagramming the letters (I've seen 'on the rampage' mean this).
'pious'+'posse'='piousposse'
'piousposse' with letters rearranged gives 'I SUPPOSE SO'.
Can you help me to learn more?
(Another definition for i suppose so that I've seen is " Er, ok".)