It may make a sheet of heavy weight on a bed (6)
I believe the answer is:
cotton
'it may make a sheet' is the definition.
The definition suggests a singular noun which matches the answer.
'heavy weight on a bed' is the wordplay.
'heavy weight' becomes 'ton' (a ton weighs a lot).
'on' means one lot of letters go next to another.
'a bed' becomes 'cot' (cot is a type of bed).
'ton' after 'cot' is 'COTTON'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for cotton that I've seen before include "Golfing man" , "Soft white substance used to make fabric - in song, Old Man River don't plant it" , "Cloth woven from a plant" , "Source of cloth" , "This wool is a fluffy wadding" .)