Late or behindhand (5)
I believe the answer is:
tardy
This clue is a double definition.
'late' is the first definition.
(I know that late can be written as tardy)
'behindhand' is the second definition.
(I've seen this before)
(Other definitions for tardy that I've seen before include "Backward" , "Rather late" , "Late - slow" , "Behindhand" , "Late, delayed" .)