Filed from 5 published puzzles

REGRETS

Set to 5 different clues across 5 published puzzles, most often "Sorry!" — The New York Times, Friday, 28 October 2005.

7 letters

Every clue on record, most used first

"Sorry!"once
The New York Times — Friday, 28 October 2005
Terse R.S.V.P.once
The New York Times — Friday, 24 December 2004
Invitation turndownonce
The New York Times — Wednesday, 13 June 2001
Brief turndown to an invitationonce
The New York Times — Monday, 11 January 1999
"Sorry, I can't come"once
The New York Times — Sunday, 21 August 1994

Other answers to these clues

ABJECT6 letters
IAMSO5 letters
IMSO4 letters
LAME4 letters
PARDONME8 letters
PITIFUL7 letters
RUING5 letters
SAD3 letters
WERE4 letters