Once in Berlin House, Edward was knocked out (9)
I believe the answer is:
exhausted
'knocked out' is the definition.
(thesaurus)
'once in berlin house edward' is the wordplay.
'once' becomes 'ex'.
'in berlin house' becomes 'haus' ('house' in German).
'edward' becomes 'ted'.
'ex'+'haus'+'ted'='EXHAUSTED'
'was' is the link.
(Other definitions for exhausted that I've seen before include "Complete fatigued" , "spent" , "Dead-beat" , "All in, really tired" , "Worn out" .)