Total, say, or just part (4)
I believe the answer is:
some
'part' is the definition.
(I've seen this before)
'total say' is the wordplay.
'total' becomes 'sum' (synonyms).
'say' indicates a 'sounds like' (homophone) clue.
'sum' sounds like 'SOME'.
'or just' is the link.
(Other definitions for some that I've seen before include "Several" , "certain" , "Undefined number" , "An unspecified quantity, not all" , "Unknown or unspecified amount or number" .)