Not yet paid as it's excessive (7)
I believe the answer is:
overdue
'not yet paid' is the definition.
(I've seen this before)
'it's excessive' is the wordplay.
I cannot quite understand how this works, but
'excessive' could be 'over' (over can mean in excess or excessively) and 'over' is found within the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'as' acts as a link.
Can you help me to learn more?
(Other definitions for overdue that I've seen before include "Behind expected time" , "Past the ETA" , "Still unpaid" , "Late arriving" , "Late for payment" .)