Sausage season starts to overwhelm Norwegian island (9)
I believe the answer is:
pepperoni
'sausage' is the definition.
(I've seen this before)
'season starts to overwhelm norwegian island' is the wordplay.
'season' becomes 'pepper' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'starts to' suggests taking the first letters.
The initial letters of 'overwhelm norwegian island' is 'oni'.
'pepper'+'oni'='PEPPERONI'
Can you help me to learn more?
(Other definitions for pepperoni that I've seen before include "Seasoned beef/pork sausage" , "Butterfly-attracting shrub" , "Type of sausage, a pizza topping" , "spicy stuff" , "what may be called a banger" .)