Bohemian soundly screwed and defeated (10)
I believe the answer is:
checkmated
'defeated' is the definition.
(checkmating is a kind of defeating)
'bohemian soundly screwed' is the wordplay.
'bohemian' becomes 'czech' (I've seen this before).
'soundly' indicates a 'sounds like' (homophone) clue.
'screwed' becomes 'mated' (I can't explain this - if you can you should give a lot more credence to this answer).
'czech' is a homophone of 'check'.
'check'+'mated'='CHECKMATED'
'and' is the link.
Can you help me to learn more?
(Another definition for checkmated that I've seen is " Moved to victory".)