Reagan Secretary of State (4)
I believe the answer is:
haig
'reagan secretary of state' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for haig that I've seen before include "British World War One field marshal" , "Douglas -, field marshal" , "WWI C-in-C" , "Earl -; British WW 1 commander-in-chief" .)