Cover floor (4)
I believe the answer is:
deck
I believe this is a double definition.
'cover' is the first definition.
(thesaurus)
'floor' is the second definition.
(I know that floor can be written as deck)
(Other definitions for deck that I've seen before include "Pack - part of record player" , "Horizontal floor on a ship" , "Set of cards" , "Adorn; level on ship" , "Pack - floor in boat" .)