Completely eject one side (8)
I believe the answer is:
outright
'completely' is the definition.
(outright means completely or totally)
'eject one side' is the wordplay.
'eject one' becomes 'out' (I can't justify this - if you can you should believe this answer much more).
'side' becomes 'right'.
'out'+'right'='OUTRIGHT'
Can you help me to learn more?
(Other definitions for outright that I've seen before include "Without restriction or reservation" , "Completely and openly - say a win" , "Completely and thoroughly" , "Without qualification" , "Totally" .)