Crossword Puzzle Miss. May zone

Clue: Miss. May zone

'Miss Saigon war zone' (NAM with 3 letters)
Famed Mississauga Mayor (MCCALLION with 9 letters)
Greenwich time zone, briefly (GMT with 3 letters)
First N.Y.C. mayor (DUANE with 5 letters)
Flood zone structure (LEVEE with 5 letters)
Item missing in this puzzle's theme that's absent as well in the fill and clues (FIFTEENTHLETTER with 15 letters)
Mayday! (SOS with 3 letters)
Miss, after vows (MRS with 3 letters)
K.C. time zone (CST with 3 letters)
New York's time zone (EASTERN with 7 letters)