Filed from 3 published puzzles

BOREON

Set to 3 different clues across 3 published puzzles, most often “Concerned” — The New York Times, Thursday, 24 November 2005.

6 letters

Every clue on record, most used first

Concernedonce
The New York Times — Thursday, 24 November 2005
Had relevance toonce
The New York Times — Tuesday, 13 October 1998
Had to do withonce
The New York Times — Sunday, 4 May 1997