Clear round left one unconscious (9)
I believe the answer is:
oblivious
'unconscious' is the definition.
(I've seen this before)
'clear round left one' is the wordplay.
'clear' becomes 'obvious' (I've seen this before).
'round' is an insertion indicator.
'left one' becomes 'li' (left abbreviation plus 1).
'obvious' going around 'li' is 'OBLIVIOUS'.
(Other definitions for oblivious that I've seen before include "Not noticing" , "Apt to forget" , "In ignorance" , "Forgetful; unaware" , "Unconscious" .)