Filed from 2 published puzzles

PENSIVE

Set to 2 different clues across 2 published puzzles, most often “Deep in thought” — The New York Times, Monday, 16 January 2006.

7 letters

Every clue on record, most used first

Deep in thoughtonce
The New York Times — Monday, 16 January 2006
Quietly thinkingonce
The New York Times — Monday, 31 May 1999

Other answers to these clues

LOST4 letters
RAPT4 letters