Has crushed mine winnings on land (6)
I believe the answer is:
ashore
'on land' is the definition.
(synonyms)
'has crushed mine winnings' is the wordplay.
'crushed' indicates an anagram.
'mine winnings' becomes 'ore' (I can't justify this - if you can you should believe this answer much more).
'has' anagrammed gives 'ash'.
'ash'+'ore'='ASHORE'
Can you help me to learn more?
(Other definitions for ashore that I've seen before include "Returned to land" , "Going on land from sea" , "Home for the sailor" , "Onto land (from the water)" , "Aground" .)