Sails (6)
I believe the answer is:
sheets
'sails' is the definition.
('sheet' can be a synonym of 'sail')
This is all the clue.
(Other definitions for sheets that I've seen before include "Bedclothes to be found on ships?" , "Pieces of paper or bedclothes" , "She set them on the bed" , "Bed coverings for the sailor's ropes" , "Flat pieces, of cloth or paper say" .)