Real Dictionary

go ahead
phrasal verb: If a process or an organized event goes ahead, it takes place or is carried out.
phrasal verb: If someone goes ahead with something, they begin to do it or make it, especially after planning, promising, or asking permission to do it.

go ahead in American English
to proceed without hesitation or delay
adjective: moving forward; advancing
noun: permission or a signal to proceed

go-ahead
A go-ahead person or organization tries hard to succeed, often by using new methods.
noun
singular noun: If you give someone or something the go-ahead, you give them permission to start doing something.
verb: to start or continue, often after obtaining permission

go-ahead in American English
advancing; not pausing

go-ahead in British English
adjective: progressive; active
noun