Definition
Clear the decks : To be used in a context when you prepare for the plan and work towards it by clearing all the hurdles.
Clear the decks : (次の仕事やプランのために)タスクを片付ける
Example
I have made this plan to pass Eiken 2. I must clear the decks to get ready for it.
英検2級に合格するために計画を立てたから、そのために準備しなきゃ。