Possible Clues:

• How one dug up the stuff, explosively
• Material covering many behinds
• What I wear when I'm understudy
• Hard-wearing blue fabric
• Material, greenish on the inside, dark outside
• Went fossicking around for material
• Material sea's thrown up around province
• Strauss' material
• Mined (anag.)
• Hard-wearing material seen in jeans