Material from the web, or feasible plan to keep a lot back (8)
I believe the answer is:
gossamer
'material from the web' is the definition.
(substance which makes cobwebs)
'feasible plan to keep a lot back' is the wordplay.
'feasible plan' becomes 'goer' (goer can mean a viable option or plan).
'to keep' indicates putting letters inside.
'a lot' becomes 'mass' (synonyms).
'back' shows that the letters should be reversed in order.
'mass' backwards is 'ssam'.
'goer' placed around 'ssam' is 'GOSSAMER'.
'or' is the link.
(Other definitions for gossamer that I've seen before include "Filaments of a spider's web" , "Flimsy, delicate material" , "Smears go onto light delicate material" , "Filmy threads seen on hedges" , "Fabric like spider's web" .)