"That makes two of us" (5)
I believe the answer is:
ditto
'that makes two of us' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ditto that I've seen before include "Dot it for the same again" , "Two dots indicating the same again" , "Mark used to indicate the word above it should be repeated" , "Repeat the word(s) above" , "As per previous" .)