Material needed to provide grassy area (4)
I believe the answer is:
lawn
This clue is a double definition.
'material' is the first definition.
(I've seen this before)
'grassy area' is the second definition.
(I've seen this before)
'needed to provide' acts as a link.
(Other definitions for lawn that I've seen before include "Fine fabric" , "Fine woven cotton" , "Linen fabric" , "sleeves composer?" , "Expanse of grass" .)