Crossword Genius

Carbon deposit in earthy matter (4)

Ross

I believe the answer is:

clay

I'm a little stuck... Click here to teach me more about this clue!

'earthy matter' is the definition.
'clay' can be an answer for 'matter' (clay is a kind of matter). I'm unsure of the 'earthy' bit.

'carbon deposit' is the wordplay.
'carbon' becomes 'C' (chemical symbol).
'deposit' becomes 'lay' (I've seen this before).
'c'+'lay'='CLAY'

'in' is the link.

Can you help me to learn more?

(Other definitions for clay that I've seen before include "slip" , "Material used by potter" , "Pigeon target" , "Muhammad Ali's original surname" , "Earth, soil" .)

I've seen this clue in the Sydney Morning Herald.
Want a hint initially instead of a full solution? Install my app