Sticky couple of marks in potter's raw material (6)
I believe the answer is:
clammy
'sticky' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for clammy that I've seen before include "Moist and adhesive" , "Stewing" , "Unpleasantly cool and humid" , "Wet and sticky" , "Dank" .)