ZAC

Set to 2 different clues across 2 published puzzles, most often “Fashion designer Posen” — The New York Times, Saturday, 8 January 2011.

3 letters

Every clue on record, most used first

Fashion designer Posenonce
The New York Times — Saturday, 8 January 2011
Actor Efron of "High School Musical"once
The New York Times — Saturday, 10 October 2009