Total or just part, say (3)
I believe the answer is:
sum
'total' is the definition.
(I know that total can be written as sum)
'part say' is the wordplay.
'part' becomes 'some' (I've seen this before).
'say' indicates a 'sounds like' (homophone) clue.
'some' sounds like 'SUM'.
'or just' is the link.
(Other definitions for sum that I've seen before include "Arithmetical problem" , "Arithmetic calculation" , "All one has" , "Aggregate, total" , "Add together" .)