Quickly gathered corrosion paved the way (7,2)
I believe the answer is:
rustled up
'quickly gathered' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'corrosion paved the way' is the wordplay.
'corrosion' becomes 'rust' (rust is a kind of corrosion).
'paved the way' becomes 'ledup' (I can't justify this - if you can you should give a lot more credence to this answer).
'rust'+'ledup'='RUSTLED UP'
Can you help me to learn more?
(Another definition for rustled up that I've seen is " prepared quickly".)