Shattered when thrown (6)
I believe the answer is:
dashed
'shattered' is the definition.
Both the answer and definition are adjectives. Perhaps there's an association between them I don't understand?
'when thrown' is the wordplay.
'when' becomes 'da' (I can't justify this - if you can you should give a lot more credence to this answer).
'thrown' becomes 'shed' ('shed' can be a synonym of 'throw').
'da'+'shed'='DASHED'
Can you help me to learn more?
(Other definitions for dashed that I've seen before include "Thrown down or ran fast" , "completely spoiled" , "Cast down as hopes may be" , "Ran hastily" , "Sprinted, rushed" .)