Mathematician contributing to group as calculator (6)
I believe the answer is:
pascal
'mathematician' is the definition.
(Pascal is an example)
'contributing to group as calculator' is the wordplay.
'contributing to' indicates a hidden word (the answer contributes to part of the clue ).
'PASCAL' is hidden within 'group as calculator'.
(Other definitions for pascal that I've seen before include "Unit of pressure, French philosopher and programming language" , "French mathematician, d. 1662 - SI unit of pressure" , "Seventeenth century French physicist" , "Unit of pressure; French scientist" , "religious philosopher" .)