Figure half-a-dozen will turn up (4)
I believe the answer is:
nine
This clue is a double definition.
'figure' is the first definition.
(I know that nine is a type of figure)
'half-a-dozen will turn up' is the second definition.
(9 resembles 6 upside down)
(Other definitions for nine that I've seen before include "No. of cat lives" , "So many" , "A number of worthies" , "It's dialled three times in an emergency" , "A stitch in time saves them" .)