Nothing in Rhode Island, suggests Louis (3)
I believe the answer is:
roi
'louis' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'nothing in rhode island' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'in' means one lot of letters goes inside another.
'rhode island' becomes 'RI' (US postal abbreviation).
'o' put within 'ri' is 'ROI'.
'suggests' acts as a link.
Can you help me to learn more?
(Other definitions for roi that I've seen before include "French king" , "Louis XIV, Le - - Soleil" .)