Smash that’s somehow returned (7)
I believe the answer is:
shatter
'smash' is the definition.
(I've seen this in another clue)
'that's somehow returned' is the wordplay.
'somehow' indicates an anagram.
'returned' becomes 'er' (I am not sure about this - if you are sure you should believe this answer much more).
'thats' with letters rearranged gives 'shatt'.
'shatt'+'er'='SHATTER'
Can you help me to learn more?
(Other definitions for shatter that I've seen before include "Break into many pieces" , "Completely upset" , "Go to pieces" , "thoroughly upset" , "Support for broken arm" .)