Calculating machine inventor, 1642 (6)
I believe the answer is:
pascal
'calculating machine inventor 1642' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pascal that I've seen before include "Seventeenth century French physicist" , "17th century French mathematician -- SI unit of pressure" , "Unit of pressure; French scientist" , "religious philosopher" , "Unit of pressure, French philosopher and programming language" .)