Beaten due to signs of having been smoking in bed (6)
I believe the answer is:
bashed
'beaten' is the definition.
'smoking in bed' is the wordplay.
'smoking' becomes 'ash' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' means one lot of letters goes inside another.
'ash' put into 'bed' is 'BASHED'.
'due to signs of having been' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for bashed that I've seen before include "Struck violently" , "Hit hard" .)