Crossword puzzle clue "issued a gag order on"

Gag order?

Places a gag order on, say

Gag order?

Nickname of the man (born 2/12/1809) who gave the address at 18A, issued the 28A/45A, was the first elected president of the 60A Party, and whose name can be found in this puzzle's main diagonal

Its first stamps were issued in 1918

U.S. visa type issued to visiting diplomats