They sell author’s latest and earliest works (9)
I believe the answer is:
retailers
'they sell' is the definition.
'author's latest and earliest works' is the wordplay.
'latest' says to take the final letters.
'and' says to put letters next to each other.
'works' indicates anagramming the letters (work can mean to twist or convulse).
The final letter of 'author' is 'r'.
'earliest' with letters rearranged gives 'etailers'.
'r'+'etailers'='RETAILERS'
(Other definitions for retailers that I've seen before include "shopkeepers" , "Sellers" , "traders" , "They sell to the public" .)