Fibrous material in rope across width in rolled-over timber (5,4)

'fibrous material' is the definition.
'glass wool' can be an answer for 'material' (glass wool is a kind of material). I am not sure about the 'fibrous' bit.

'rope across width in rolled-over timber' is the wordplay.
I cannot really understand how this works, but
'width' could be 'w' (abbreviation in geometry) and 'w' is located in the answer.
'rope' could be 'lasso' (lasso is a kind of rope) and 'lasso' is found within the remaining letters.
'over' could be 'o' (cricket abbreviation) and 'o' is present in the answer.
This explanation may well be incorrect...

'in' is the link.

Can you help me to learn more?