Melanesian for one day, I lie about (7,8)

I believe the answer is:
solomon islander
'i lie about' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'melanesian for one day' is the wordplay.
I cannot really see how this works, but
'one' could be 'solo' (I've seen this before) and 'solo' is found in the answer.
'day' could be 'mon' (short for Monday) and 'mon' is found within the answer.
The remaining letters 'islander' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for solomon islander that I've seen before include "person living in the Pacific" , "one from Oceania" .)
