Filed from 3 published puzzles

DOGGED

Set to 3 different clues across 3 published puzzles, most often “Tenacious” — The New York Times, Thursday, 13 November 1997.

6 letters

Every clue on record, most used first

Tenaciousonce
The New York Times — Thursday, 13 November 1997
Perseveringonce
The New York Times — Friday, 21 June 1996
Followed tenaciouslyonce
The New York Times — Tuesday, 14 March 1995

Other answers to these clues

ATIT4 letters
SEDULOUS8 letters