Mole appearing as grey on ground (6)
I believe the answer is:
groyne
'mole' is the definition.
(protective structure extending into the water)
'grey on ground' is the wordplay.
'ground' is an anagram indicator ('grind' the letters into a new form).
'grey'+'on'='greyon'
'greyon' anagrammed gives 'GROYNE'.
'appearing as' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for groyne that I've seen before include "Mole" , "Beach breakwater" , "that stands against the tide" , "Anti-erosion breakwater" , "Barrier built on beach" .)