basically means to leave. can be used as an alternative to the word dust or as an insult to tell someone to leave you alone.
Nick: negroid u r vexing me , duck away blud!
Clarke: oh dear god , im very sorry kind sir, i will duck away immediately to avoid n e further confrontation.
Ritchie: Shizzle, its the po po , duck away manz
Rippa: na dont worry homie , i will just draw for my 9 and slew dem wastemanz
To tell someone to get lost.
"Matt you are a homosexual, Duck away!"