With shiny new coat, maybe grass skirts get bigger (7)

'with shiny new coat maybe' is the definition.
I can't tell whether this definition defines the answer.

'grass skirts get bigger' is the wordplay.
'grass' becomes 'rice'.
'skirts' means to remove the middle letters (retain the edges).
'get bigger' becomes 'waxed' (I can't justify this - if you can you should give a lot more credence to this answer).
'rice' with its middle removed is 're'.
're'+'waxed'='REWAXED'

Can you help me to learn more?