He has set about making rope (5)
I believe the answer is:
sheet
'rope' is the definition.
(I know that sheet is a type of cordage)
'he has set about' is the wordplay.
'has' means one lot of letters go next to another.
'about' indicates anagramming the letters.
'he' put after 'set' is 'sethe'.
'sethe' anagrammed gives 'SHEET'.
'making' acts as a link.
(Other definitions for sheet that I've seen before include "Piece of linen, paper, etc" , "Piece of paper; nautical rope" , "Piece of paper or bedding" , "Item of bedlinen" , "Piece of paper or bedlinen" .)