The kiddie can add up (3)
I believe the answer is:
tot
I believe this is a double definition.
'the kiddie' is the first definition.
(I've seen this in another clue)
'add up' is the second definition.
(I know that add up can be written as tot)
'can' acts as a link.
(Other definitions for tot that I've seen before include "finger, possibly" , "Small amount of spirits" , "Small measure for a small child" , "slug?" , "Calculate" .)