Author turned green by finishing with the mail (5,4)

'author' is the definition.
(I know that Emily Post is a author)

'turned green by finishing with the mail' is the wordplay.
'turned' says the letters should be written in reverse.
'green' becomes 'lime' (lime is a shade of green).
'finishing' suggests the final letters (the letter which finishes the word).
'with' says to put letters next to each other.
'the mail' becomes 'post' (synonyms).
The final letter of 'by' is 'y'.
'lime' in reverse letter order is 'emil'.
'emil'+'y'+'post'='EMILY POST'