Digit, number (6)
I believe the answer is:
figure
I believe this clue is a double definition.
'digit' is the first definition.
(figure is a kind of digit)
'number' is the second definition.
(figure is a kind of whole number)
(Other definitions for figure that I've seen before include "Number; statue" , "Symbol, numeral" , "Judge to be probable, estimate" , "Shape; amount of money" , "Statistic - physique" .)