Harry S —, president of the US from 1945-53 (6)

I believe the answer is:
truman
(Other definitions for truman that I've seen before include "American president who ordered use of atomic bomb" , "Harry S ...... was USA president 1945-53" , "Harry S ... former US president" , "- Capote, US novelist" , "Harry S. ---, US Pres." .)