Reason for insurance being cancelled initially: too old (7)
I believe the answer is:
overage
'too old' is the definition.
(I've seen this before)
'reason for insurance being cancelled initially' is the wordplay.
'reason for insurance' becomes 'age' (I can't explain this - if you can you should believe this answer much more).
'being cancelled' becomes 'over' (I've seen this in another clue).
'initially' means one lot of letters go next to another (some letters go before others).
'age' put after 'over' is 'OVERAGE'.
Can you help me to learn more?
(Other definitions for overage that I've seen before include "Too old to qualify or a surplus of goods" , "Too old to be eligible" , "Older than certain limit" , "Excessively old" , "Excess" .)