Filed from 3 published puzzles

ROOTLET

Set to 3 different clues across 3 published puzzles, most often “Underground branch” — The New York Times, Friday, 14 May 2010.

7 letters

Every clue on record, most used first

Underground branchonce
The New York Times — Friday, 14 May 2010
Tiny plant partonce
The New York Times — Sunday, 10 August 2003
Ivy offshootonce
The New York Times — Wednesday, 15 March 1995