Adds up the number of wrecks (6)
I believe the answer is:
totals
This might be a double definition.
'adds up' is the first definition.
('total' can be a synonym of 'add up')
'number of wrecks' is the second definition.
'totals' can be an answer for 'wrecks' (I've seen this in another clue). I'm not certain of the 'number of' bit.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for totals that I've seen before include "Adds up the entire amounts" , "Sums and aggregates" , "Aggregations or sums" , "Kills" .)