clear the decks, to

To  prepare  for  action. This  term  comes  from  naval warfare. In the times of wooden sailing ships, a crew prepared for battle by fastening down or removing all loose objects on the decks, lest they get in the  way  or  cause  an  injury. By  the  eighteenth  century  the  term  was  being used  to  mean  getting  ready  for  any  major  undertaking  by  getting  small details out of the way. See also BATTEN DOWN THE HATCHES.