Author starts to smile at last (8)
I believe the answer is:
salinger
'author' is the definition.
(JD Salinger)
'starts to smile at last' is the wordplay.
'starts to' suggests taking the first letters.
'last' becomes 'linger' (both can mean to remain).
The initial letters of 'smile at' is 'sa'.
'sa'+'linger'='SALINGER'
(Other definitions for salinger that I've seen before include "'JD..., author of The Catcher in the Rye (8)'" , "J. D. ..., author of Catcher in the Rye" , "US novelist" , "US author of The Catcher in the Rye" , "Jerome D ........ wrote ` ` The Catcher in the Rye' '" .)