Boy stopped — once made fine pottery (7)
I believe the answer is:
celadon
'pottery' is the definition.
(I've seen this before)
'boy stopped once made fine' is the wordplay.
I cannot quite see how this works, but
'boy' could be 'don' and 'don' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for celadon that I've seen before include "pottery" , "Green" , "Greyish-green porcelain" .)