Doing as ordered one's reaching conclusion (9)
I believe the answer is:
diagnosis
'conclusion' is the definition.
'doing as ordered one's' is the wordplay.
'ordered' is an anagram indicator.
'one's' becomes 'is' (Roman numeral).
'doing'+'as'='doingas'
'doingas' with letters rearranged gives 'diagnos'.
'diagnos'+'is'='DIAGNOSIS'
'reaching' acts as a link.
(Other definitions for diagnosis that I've seen before include "analysis" , "Identification of a problem from its symptoms" , "Interpretation of" , "doctor's opinion" , "Identification of an illness" .)