Weight applied to bed sheet material (6)
I believe the answer is:
cotton
'sheet material' is the definition.
'cotton' can be an answer for 'material' (cotton is a kind of material). I'm not certain of the 'sheet' bit.
'weight applied to bed' is the wordplay.
'weight' becomes 'ton' (unit of weight).
'applied to' says to put letters next to each other.
'bed' becomes 'cot' (cot is a type of bed).
'ton' put after 'cot' is 'COTTON'.
Can you help me to learn more?
(Other definitions for cotton that I've seen before include "Material" , "Plant fibre for fabrics" , "Natural textile fibre" , "Cloth made from fine hairs of seed pod" , "This wool is a fluffy wadding" .)