Stone age blocks meld amorphously (7)
I believe the answer is:
emerald
'stone' is the definition.
(type of gemstone)
'age blocks meld amorphously' is the wordplay.
I cannot quite see how this works, but
'age' could be 'era' (both can mean a long time) and 'era' is located in the answer.
an anagram of 'meld' is 'emld' which is present in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for emerald that I've seen before include "Small size of type, in printing" , "Precious green stone" , "Led mare (anag.)" , "On of the Greens" , "Green - jewel" .)