Sentence:  'Mid the rattle of blocks and the tramp of the crew,<br />Hisses the rain of the rushing squall;<br />The sails are aback from <WSD>clew</WSD> to <WSD>clew</WSD>,<br />And now is the moment for "MAINSAIL, HAUL!" 
Meaning of the word marked with <WSD> tags:  The lower corner(s) of a sail to which a sheet is attached for trimming the sail (adjusting its position relative to the wind); the metal loop or cringle in the corner of the sail, to which the sheet is attached.  The trailing corner relative to the wind direction.