Above and just behind the clock (7)
I believe the answer is:
overdue
'behind the clock' is the definition.
I can't judge whether this definition defines the answer.
'above and just' is the wordplay.
'above' becomes 'over' (I've seen this before).
'and' means one lot of letters go next to another.
'just' becomes 'due' (I've seen this in another clue).
'over'+'due'='OVERDUE'
Can you help me to learn more?
(Other definitions for overdue that I've seen before include "Behind schedule" , "Beyond the designated time for payment" , "Behindhand" , "Later than expected" , "Later than the appointed time, as for bill payment" .)