Mountain bike finally ready? Good (7)
I believe the answer is:
benefit
'ready? good' is the definition.
'benefit' can be an answer for 'good' (benefit is a kind of good). I am not sure about the 'ready?' bit.
'mountain bike finally' is the wordplay.
'mountain' becomes 'ben' (ben is a kind of mountain).
'bike finally' becomes 'efit' (I can't justify this - if you can you should give a lot more credence to this answer).
'ben'+'efit'='BENEFIT'
Can you help me to learn more?
(Other definitions for benefit that I've seen before include "Advantage (from social security?)" , "Advantage; dole" , "Charity event" , "Payment" , "Something that aids" .)