High-ranking officer (5,3)
'high-ranking officer' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for general that I've seen before include "The senior officer is common and widespread" , "Officer of the highest rank" , "Catholic" , "Normal; military rank" , "Enlarge for senior army officer" .)
(Other definitions for brass hat that I've seen before include "official of the first rank" , "High-ranking official or officer with metal headgear?" , "Senior mil. officer (slang)" , "Senior army officer" , "High-ranking officer in armed forces (colloq.)" .)