Make up time lost in first class (1-3)
I believe the answer is:
a-one
'first class' is the definition.
(A1 can mean excellent or first class)
'make up time lost' is the wordplay.
'make up' becomes 'atone' (to atone for something is to make up for it).
'time' becomes 't' (abbreviation).
'lost' is a deletion indicator.
'atone' with 't' removed is 'A-ONE'.
'in' acts as a link.
(Other definitions for a-one that I've seen before include "Of the highest quality" , "First class!" .)