Come across a drunkard, upside down and unconscious (8)
I believe the answer is:
comatose
'unconscious' is the definition.
(similar in meaning)
'come across a drunkard upside down' is the wordplay.
'across' indicates putting letters inside.
'drunkard' becomes 'sot' (synonyms).
'upside down' says the letters should be written in reverse.
'sot' in reverse letter order is 'tos'.
'a'+'tos'='atos'
'come' enclosing 'atos' is 'COMATOSE'.
'and' is the link.
(Other definitions for comatose that I've seen before include "Deeply unconscious" , "Somnolent" , "Very drowsy, perhaps unconscious" , "In a drowsy or semi-conscious state" , "Fast asleep" .)