Material from a pit, dug up (5)
I believe the answer is:
denim
'material from a pit' is the definition.
'denim' can be an answer for 'material' (type of fabric). I'm not certain of the 'from a pit' bit.
'dug up' is the wordplay.
'dug' becomes 'mined' (dug into the ground).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'mined' in reverse letter order is 'DENIM'.
Can you help me to learn more?
(Other definitions for denim that I've seen before include "Hard-wearing clothing material, twilled cotton" , "Coloured cotton twill" , "Hard-wearing blue fabric" , "Coarse durable twill-weave cotton fabric" , "Fabric used for jeans" .)