Breathable fabric (4)
'breathable fabric' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mesh that I've seen before include "Undeviating" , "Interlaced structure" , "Piece of netting" , "Become entangled - become engaged" , "Get engaged" .)
(Other definitions for linen that I've seen before include "Material made from flax" , "Cloth woven flax fibres" , "Fabric woven from flax fibres" , "Fine cloth for Lenin" , "Flax product" .)