Clue: Revered figure penning line with series of postings? That's valuable material (4,6)
Answer: GOLD THREAD
Explanation: Definition: valuable material
GOD="Revered figure" around/"penning" L (line), plus THREAD="series of postings" as in a thread of online comments 
I may be reading too much into the surface: Larkin penned a line at the end of *Aubade* about postmen going from house to house, a "series of postings"