Sophocles regularly promoted such reflection (4)
I believe the answer is:
echo
'reflection' is the definition.
(I know that echo is a type of reflection)
'sophocles regularly promoted' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'promoted' shows that the letters should be reversed in order (going up, in a down clue).
The alternating letters of 'sophocles' are 'ohce'.
'ohce' back-to-front is 'ECHO'.
'such' is the link.
(Other definitions for echo that I've seen before include "Marked by heat" , "ring" , "Mimic" , "One who slavishly copies" , "Repeating of sound" .)