Reportedly in favour of a number (4)
I believe the answer is:
four
'number' is the definition.
(I know that four is a type of digit)
'reportedly in favour' is the wordplay.
'reportedly' shows a homophone (sound like).
'in favour' becomes 'for' (as in being for a particular cause).
'for' sounds like 'FOUR'.
'of a' acts as a link.
(Other definitions for four that I've seen before include "10 cleared of misuse of fortune" , "Number in quartet" , "Figure" , "Boundary hit (cricket)" , "teatime?" .)