Tent-cloth (6)
I believe the answer is:
canvas
This clue is a double definition.
'tent' is the first definition.
(e.g. under canvas means under a tent)
'cloth' is the second definition.
(I know that canvas is a type of piece of cloth)
(Other definitions for canvas that I've seen before include "Cloth used for tents, sails etc" , "End of a racing boat; coarse cloth" , "Cloth for painting etc" , "Material for tents, etc" , "Strong coarse cloth" .)