Get Roget translated by England's top silk (9)
I believe the answer is:
georgette
'silk' is the definition.
(I have seen 'thin silk' mean 'georgette' so perhaps 'silk' could also mean 'georgette')
'get roget translated by england's top' is the wordplay.
'translated' indicates an anagram.
'by' says to put letters next to each other.
'top' indicates taking the first letters (in a down clue, the first letter is top).
The first letter of 'englands' is 'e'.
'get'+'roget'='getroget'
'getroget' anagrammed gives 'georgett'.
'georgett'+'e'='GEORGETTE'
(Other definitions for georgette that I've seen before include "novelist Heyer?" , "Miss Heyer?" , "girl" , "Fabric" , "thin silk" .)