Unqualified to sum up (5)
I believe the answer is:
total
I believe this clue is a double definition.
'unqualified' is the first definition.
('total' can be a synonym of 'unqualified')
'sum up' is the second definition.
('total' can be a synonym of 'sum up')
'to' is the link.
(Other definitions for total that I've seen before include "outright" , "Absolute; sum" , "The whole number" , "Complete; add up" , "Whole amount" .)