Totals SUV, losing velocity by milliseconds (4)
I believe the answer is:
sums
'totals' is the definition.
(I know this)
'suv losing velocity by milliseconds' is the wordplay.
'losing' is a deletion indicator.
'velocity' becomes 'v' (scientific abbreviation).
'by milliseconds' becomes 'ms' (I am not sure about this - if you are sure you should believe this answer much more).
'suv' with 'v' taken out is 'su'.
'su'+'ms'='SUMS'
Can you help me to learn more?
(Other definitions for sums that I've seen before include "Quantities obtained by addition" , "Exercises in arithmetic" , "Amounts of money" , "Calculations" .)