Island north of Australia was aware of one of Thatcher's ministers, reportedly (3,7)

'island' is the definition.
(New Britain is an example)

'north of australia was aware of one of thatcher's ministers reportedly' is the wordplay.
I cannot really understand how this works, but
'north' could be 'n' (abbreviation) and 'n' is found in the answer.
'australia' could be 'a' (abbreviation for Australia) and 'a' is found in the answer.
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
'reportedly' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?