My prefix, is not very good
My infix, a bird not in wood
My suffix, might be the answer
Fork, Mountain, London, Cancer
Could it be
malarkey? This word means "meaningless talk; nonsense".
mal is a prefix for "in a faulty manner" like malfunction
lark is a bird
key is one of the synonyms to "answer"
"Fork, Mountain, London, Cancer" is kind of malarkey :-)