Extra expected, late arriving (7)
I believe the answer is:
'late arriving' is the definition.
(I've seen this before)
'extra expected' is the wordplay.
'extra' becomes 'over' (both can mean left over).
'expected' becomes 'due' (similar in meaning).
(Other definitions for overdue that I've seen before include "(Of library books) late" , "after the time specified" , "Beyond the designated time for payment" , "In arrears" , "Behindhand" .)