As many as (4)
'as many as' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for up to that I've seen before include "Busy with" , "Engaged in doing" , "As far as or as many as" , "working at > till" , "Incumbent upon" .)
(Other definitions for upto that I've seen before include "Capable of or engaged in" , "Equal to or occupied with" , "'Having the requisite qualities for (2,2)'" , "As far as; ready for" , "As far as; occupied with (colloq.)" .)