Complete; sum (5)
I believe the answer is:
total
This clue is a double definition.
'complete' is the first definition.
(similar in meaning)
'sum' is the second definition.
(I know that sum can be written as total)
(Other definitions for total that I've seen before include "Complete, entire amount" , "Aggregate amount" , "outright" , "Not qualified" , "to give the final figure" .)