Filed from 14 published puzzles

BASIS

Set to 6 different clues across 14 published puzzles, most often “Foundation” — The New York Times, Tuesday, 9 May 2006.

5 letters

Every clue on record, most used first

Foundation6 times
The New York Times — Tuesday, 9 May 2006
Groundwork4 times
The New York Times — Wednesday, 5 September 2007
Bottomonce
The New York Times — Friday, 26 January 2007
Underlying principleonce
The New York Times — Tuesday, 28 March 2006
Amount from which to figure sale profitonce
The New York Times — Wednesday, 31 August 2005
Groundsonce
The New York Times — Monday, 7 March 1994

Other answers to these clues

AREA4 letters
BASE4 letters
BED3 letters
CAUSE5 letters
DREGS5 letters
FANNY5 letters
FOOT4 letters
FOOTING7 letters
PLANTINGTHESEED15 letters
RATIONALE9 letters
SEAT4 letters