In no position to act so came to a fresh arrangement (8)
I believe the answer is:
comatose
'in no position to act' is the definition.
(someone in a coma is unable to do things)
'so came to a fresh arrangement' is the wordplay.
'a fresh arrangement' is an anagram indicator (letters arranged in a new way).
'so'+'came'+'to'='socameto'
'socameto' is an anagram of 'COMATOSE'.
(Other definitions for comatose that I've seen before include "Sandman called" , "Very drowsy, perhaps unconscious" , "Come to as in drowsy condition" , "In a drowsy or semi-conscious state" , "Insensible or unconscious" .)